How to use Ghostscript

## Table of contents

> - Invoking Ghostscript
>   - Help at the command line: `gs -h`
> - Security Issues
> - Input from a pipe
> - Selecting an output device
>   - Printer resolution
>   - Output to files
>     - One page per file
>     - Output to a pipe
>     - Output to graphics file formats
>     - Bounding box output
>   - Choosing paper size
>   - Changing the installed default paper size
> - How Ghostscript finds files
>   - Finding PostScript Level 2 resources
>   - Font lookup
>   - Temporary files
> - Summary of environment variables
> - Using Ghostscript with PDF files
>   - PDF files from standard input
>   - Switches for PDF files
>   - Problems interpreting a PDF file
> - Notes on specific platforms
>   - Unix
>   - VMS
>     - Using X Windows on VMS
>   - MS Windows
>   - MS-DOS
>   - X Windows
>     - X resources
>     - Working around bugs in X servers
>     - X fonts
>     - Using Ghostscript fonts on X displays
>     - X device parameters
>   - SCO Unix
> - Switches
>   - General switches
>     - Input control
>     - File searching
>     - Setting parameters
>     - Suppress messages
>   - Parameter switches (`-d` and `-s`)
>     - Rendering parameters
>     - Page parameters
>     - Font-related parameters
>     - Interaction-related parameters
>     - Device and output selection parameters
>     - Other parameters
> - Improving performance
> - Debugging
> - Appendix: Paper sizes known to Ghostscript
> - Appendix: X default font mappings
>   - Standard X servers
>     - Regular fonts
>     - Symbol fonts
>     - Dingbat fonts
>   - Sun OpenWindows

For other information, see the Ghostscript overview, the new user's documentation on previewers and, if necessary, how to install Ghostscript.

# Invoking Ghostscript

The command line to invoke Ghostscript is essentially the same on all systems, although the name of the executable program itself may differ among systems. For instance, to invoke Ghostscript on Unix:

> `gs` [switches] {filename 1} ... [switches] {filename N} ...

> Ghostscript's name on different systems
> System |  | Ghostscript's name
> Unix |  | `gs`
> VMS |  | `gs`
> DOS & MS Windows 3 |  | `gs386`
> MS Windows 95/98 |  | `gswin32`
> MS Windows 95/98 command line |  | `gswin32c`
> OS/2 |  | `gsos2`

Note, though, that on a system with a windowed graphical user interface, it's common to use Ghostscript through a previewer, so you should read the section about previewers in the documentation for new users.

Ghostscript is capable of interpreting PostScript, encapsulated PostScript (EPS), DOS EPS (EPSF), and -- if the executable was built for it -- Adobe Portable Document Format (PDF). The interpreter reads and executes the files in sequence, using the method described under "File searching" to find them. After doing this, it reads further lines of PostScript language commands from the primary input stream, normally the keyboard, interpreting each line separately. To quit the interpreter, type "`quit`". The interpreter also quits gracefully if it encounters end-of-file or control-C.

The interpreter recognizes many switches. A switch may appear anywhere in the command line, and applies to all files named after it on the line. Many of the switches include "`=`" followed by a parameter.

## Help at the command line: `gs -h`

You can get a brief help message by invoking Ghostscript with the `-h` or `-?` switch, like this:

> `gs -h
> gs -?`

(Of course, for "`gs`" use the right command for your system.) The message shows for this executable

- its version
- the format of the command to invoke it
- a few of the most useful switches
- the formats it can interpret
- the devices for which it can produce output
- where it looks for font files
- where and how to send bug reports

# Security

Ghostscript implements a full-featured programming language, with access to the filesystem and the ability to control a diverse set of devices. As such, there are potential security implications.

The first line of defense is to use the security mechanisms provided by Ghostscript. If you're running arbitrary PostScript files (for example, those sent through email or downloaded from the Web), make sure to use the -dSAFER option. Otherwise, you are opening up your entire filesystem to potentially malicious code.

By default, Ghostscript opens up read access to the entire filesystem. In general, if you're just viewing or printing documents, this does not pose a significant security risk. However, if there is a chance that the output of Ghostscript can leak sensitive information, also set the -DPARANOIDSAFER option. Note, however, that this option is incompatible with some scripts and wrappers, including gv and related viewer apps.

We plan to make -dSAFER the default in future versions of Ghostscript. Since most people use Ghostscript to print and view documents, rather than to run scripts written in the PostScript language, this will provide additional safety with little hassle for most users. If you are using Ghostscript as a scripting language and need unfettered access to the filesystem, use the -dNOSAFER flag to signal explictly that you wish the PostScript code to have full access to the file system. Currently, this flag has no effect, but it will insure than your scripts execute as expected in future versions.

While we've tried to patch all known security problems, there is no guarantee that we've caught them all. Ghostscript is a complex application written in C. Buffer overflows and other exploits remain a distinct possibility. Thus we recommend that, whenever possible, Ghostscript should run in a secure "sandbox" environment, making use of the security mechanisms of the underlying operating system. In particular, we urge GNU/Linux distributors to invoke Ghostscript from the print subsystem in a chroot'ed environment, and never as root.

We will continue to be vigilant regarding security issues. As always, apply security updates promptly.

# Input from a pipe

As noted above, one normally specifies input with file names on the command line. However, one can also "pipe" input into Ghostscript by using the special file name "`-`" or "`-_`", for instance

> {some program producing PS} `| gs` {...options...} `-`
> {some program producing PS} `| gs` {...options...} `-_`

These switches differ from a named file in two respects:

1. When Ghostscript finishes reading from the pipe, it quits rather than going into interactive mode. Because of this, these switches are really only useful as the last argument on the command line.
2. These switches can't be used to pipe PDF input to Ghostscript. See "Using Ghostscript with PDF files" below.

The difference between "`-`" and "`-_`" is that "`-`" reads the input one character at a time, which is useful for programs such as GSview that generate input for Ghostscript dynamically and watch for some response, whereas "`-_`" reads the input in blocks, which is more efficient for ordinary (batch) execution.

# Selecting an output device

Ghostscript may be built to handle multiple output devices, and it normally opens and directs output to the first one built in. Ghostscript's `gs -h` help message lists the output devices known to the executable. Once you invoke Ghostscript you can also find out what devices are available by "`devicenames ==`" at its command prompt.

A little more information about devices appears near the beginning of the files `devs.mak` (for Aladdin's own drivers) and `contrib.mak` (for user-contributed drivers) used to build Ghostscript. (If you got Ghostscript under the Aladdin Free Public License, the person or place from which you got it is also required to make the source code available to you; if you got it under the GNU General Public License (GPL), see the GNU General Public License for more information.)

To use device xyz as the initial output device, use the command-line switch

> `-sDEVICE=`xyz

Note that this switch must precede the name of the first input file, and only its first use has any effect. For example, for printer output in a configuration that includes an Epson printer driver, instead of just "`gs myfile.ps`" you might use

> `gs -sDEVICE=epson myfile.ps`

Alternatively, once you invoke Ghostscript and have its own command prompt you can type

> `(epson) selectdevice
> (myfile.ps) run`

All output then goes to the Epson printer instead of the display until you do something to change devices. You can switch devices at any time by using the `selectdevice` procedure, for instance like one of these:

> `(vga) selectdevice
> (epson) selectdevice`

A third possibility is to define an environment variable `GS_DEVICE` with the name of your desired default device. The order of precedence for these alternatives, highest to lowest, is:

> `selectdevice` |  | Highest precedence
> (command line) |  |
> `GS_DEVICE` |  |
> (first device built in) |  | Default; lowest precedence

## Printer resolution

Some printers can print at several different resolutions, letting you balance resolution against printing speed. To select the resolution on such a printer, use the `-r` switch:

> `gs -sDEVICE=`printer`-r` XRES `x` YRES

For example, on Epson-compatible printers you have these choices:

> `gs -sDEVICE=epson` |  | `-r60x72` |  | 9-pin |  | lowest resolution |  | fastest
> |  | `-r240x72` |  |  |  | highest |  | slowest
> |  | `-r60x60` |  | 24-pin |  | lowest |  | fastest
> |  | `-r360x180` |  |  |  | highest |  | slowest

## Output to files

If you select a printer as the output device, Ghostscript also allows you to control where the device sends its output. On DOS and MS Windows systems, output normally goes directly to the printer (`PRN`); on Unix or VMS systems normally to a temporary file for later printing. To send the output to a file, use the `-sOutputFile=` switch (for compatibility with older versions of Ghostscript, `-sOUTPUTFILE=` also works). For instance, to direct all output into the file `ABC.xyz`, use

> `gs -sOutputFile=ABC.xyz`

The file name follows the PostScript convention that if a name begins with `%`, the name must be in the form `%`filedevice or `%`filedevice`%`file. The legal values of filedevice are system-dependent, but the following have consistent meanings across systems:

> "%{filedevice}%{file}" in `-sOutputFile=`
> filedevice |  | Meaning
> `%os%xyz` |  | An ordinary file named `xyz`
> `%pipe%cmd` |  | (if supported) A pipe to an instance of the command `cmd`
> `%stdout` |  | The standard output file

Note that on DOS and MS Windows systems, the `%` character has a special meaning for the command processor (shell), so you will have to double it, e.g., for a pipe on MS Windows,

> `gs -sOutputFile=%%pipe%%cmd`

### One page per file

You can also tell Ghostscript to put each page of output in a separate file. To send output to a series of files each representing a single page, use in the filename the `printf` format specifier "`%d`" (or its extended form like "`%02d`"); for instance

> "%{n}d" in `-sOutputFile=`
> Output specification |  | Produces the series of 1-page files
> `-sOutputFile=ABC%d.xyz` |  | `ABC1.xyz` ... `ABC10.xyz` ...
> `-sOutputFile=ABC%03d.xyz` |  | `ABC001.xyz` ... `ABC010.xyz` ...

As noted above, on DOS and MS Windows systems, you will have to double the `%` character, e.g.,

> `gs -sOutputFile=ABC%%03d.xyz`

### Output to a pipe

On Unix and (32-bit) MS Windows systems you can use this switch to send output directly to a pipe. For example, to pipe the output to `lpr`, use the command

> `gs -sOutputFile=\|lpr`

or, as noted above,

> `gs -sOutputFile=%pipe%lpr`

(doubling the `%` characters on MS Windows systems, as noted above.) You can also send output to standard output for piping in the usual way supported by the system:

> `gs -sOutputFile=- -q |` ...

or, as noted above,

> `gs -sOutputFile=%stdout -q |` ...

(again, doubling the `%` character on MS Windows systems.) In this case you must also use the `-q` switch to prevent Ghostscript from writing messages to standard output which become mixed with the intended output stream.

### Output to graphics file formats

File formats like PCX and PBM are also "devices". When you select a file format as the "device", you must also specify an output file, for instance

> `gs -sDEVICE=pcxmono -sOutputFile=xyz.pcx`

Here, as with printable files, you can use "`%d`" ("`%%d`" on DOS and MS Windows) to specify one page per output file.

### Bounding box output

There is a special `bbox` "device" that just prints the bounding box of each page. You select it in the usual way:

> `gs -dNOPAUSE -dBATCH -sDEVICE=bbox`

It prints the output in a format like this:

>     %%BoundingBox: 14 37 570 719
>     %%HiResBoundingBox: 14.308066 37.547999 569.495061 718.319158

Currently, it always prints the bounding box on `stderr`; eventually, it should also recognize `-sOutputFile=`.

Note that this device, like other devices, has a resolution and a (maximum) page size. As for other devices, the product (resolution x page size) is limited to approximately 500K pixels. By default, the resolution is 4000 DPI and the maximum page size is approximately 125", or approximately 9000 default (1/72") user coordinate units. If you need to measure larger pages than this, you must reset both the resolution and the page size in pixels, e.g.,

> `gs -dNOPAUSE -dBATCH -sDEVICE=bbox -r100 -g500000x500000`

## Choosing paper size

Ghostscript is distributed configured to use U.S. letter paper as its default page size. There are two ways to select other paper sizes from the command line:

- If the desired paper size is listed in the section on paper sizes known to Ghostscript below, you can select it as the default paper size for a single invocation of Ghostscript by using the `-sPAPERSIZE=` switch, for instance

  > `-sPAPERSIZE=a4
  > -sPAPERSIZE=legal`

- Otherwise, let w be the desired paper width and h be the desired paper height, in 1/72" units. You can set the page size using the pair of switches

  > `-dDEVICEWIDTHPOINTS=`w `-dDEVICEHEIGHTPOINTS=`h

Individual documents can (and often do) specify a paper size, which takes precedence over the default size. To force a specific paper size and ignore the paper size specified in the document, select a paper size as just described, and also include the `-dFIXEDMEDIA` switch on the command line.

## Changing the installed default paper size

You can change the installed default paper size in installing Ghostscript or later, by editing the initialization file `gs_init.ps`. Find the consecutive lines

> `% Optionally choose a default paper size other than U.S. letter.
> % (a4)`

Then to make A4 the default paper size, uncomment the second line to change this to

> `% Optionally choose a default paper size other than U.S. letter.
> (a4)`

For `a4` you can substitute any paper size Ghostscript knows.

# How Ghostscript finds files

When looking for initialization files (`gs_*.ps`, `pdf_*.ps`), font files, the `Fontmap` file, and files named on the command line, Ghostscript first tests whether the file name specifies an explicit directory.

> Testing a file name for an explicit directory
> System |  | Does the name ...
> Unix |  | Begin with `/`, `./` or `../` ?
> DOS or MS Windows |  | Have `:` as its second character, or begin with `/`, `\`, `./`, `../`, `.\`, or `..\` ?
> VMS |  | Contain a node, device, root, or directory specification?

If the test succeeds, the file name specifies an explicit directory and Ghostscript tries to open the file using the name given. Otherwise it tries directories in this order:

1. The current directory (unless disabled by the `-P-` switch);
2. The directories specified by `-I` switches in the command line, if any;
3. The directories specified by the `GS_LIB` environment variable, if any;
4. The directories specified by the `GS_LIB_DEFAULT` macro (if any) in the makefile when this executable was built.

`GS_LIB_DEFAULT`, `GS_LIB`, and the `-I` parameter may specify either a single directory or a list of directories separated by a character appropriate for the operating system ("`:`" on Unix systems, "`,`" on VMS systems, and "`;`" on DOS systems). We think that trying the current directory first is a very bad idea -- it opens serious security loopholes and can lead to very confusing errors if one has more than one version of Ghostscript in one's environment -- but when we attempted to change it, users insisted that we change it back. You can disable looking in the current directory first by using the `-P-` switch.

Note that Ghostscript does not use this file searching algorithm for the `run` or `file` operators: for these operators, it simply opens the file with the name given. To run a file using the searching algorithm, use `runlibfile` instead of `run`.

## Finding PostScript Level 2 resources

Ghostscript uses a completely different rule for looking for files containing PostScript Level 2 "resources": per the Adobe documentation, it concatenates together

1. the value of the system parameter `GenericResourceDir` (initially `/Resource/`)
2. the name of the resource category (for instance, `ProcSet`)
3. the value of the system parameter `GenericResourcePathSep` (initially "`/`")
4. the name of the resource instance (for instance, `CIDInit`)

To look up fonts, after exhausting the search method described in the next section, it concatenates together

1. the value of the system parameter `FontResourceDir` (initially `/Resource/Font/`)
2. the name of the resource font (for instance, `Times-Roman`)

Note that even though the system parameters are named "somethingDir", they are not just plain directory names: they have "`/`" on the end, so that they can be concatenated with the category name or font name.

## Font lookup

Ghostscript has a slightly different way to find the file containing a font with a given name. This rule uses not only the search path defined by `-I`, `GS_LIB`, and `GS_LIB_DEFAULT` as described above, but also the directory that is the value of the `FontResourceDir` system parameter, and an additional list of directories that is the value of the `GS_FONTPATH` environment variable (or the value provided with the `-sFONTPATH=` switch, if present).

At startup time, Ghostscript reads in the `Fontmap` files in every directory on the search path (or in the list provided with the `-sFONTMAP=` switch, if present): these files are catalogs of fonts and the files that contain them. (See the documentation of fonts for details.) Then, when Ghostscript needs to find a font that isn't already loaded into memory, it goes through a series of steps.

- First, it looks up the font name in the combined Fontmaps. If there is an entry for the desired font name, and the file named in the entry can be found in some directory on the general search path (defined by `-I`, `GS_LIB`, and `GS_LIB_DEFAULT`), and the file is loaded successfully, and loading it defines a font of the desired name, that is the end of the process.
- If this process fails at any step, Ghostscript looks for a file whose name is the concatenation of the value of the `FontResourceDir` system parameter and the font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end. The value of `FontResourceDir` is normally the string `/Resource/Font/`, but it can be changed with the `setsystemparams` operator: see the PostScript Language Reference Manual for details.
- If that fails, Ghostscript then looks for a file on the general search path whose name is the desired font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end.
- If that too fails, Ghostscript looks at the `GS_FONTPATH` environment variable (or the value provided with the `-sFONTPATH=` switch, if present), which is also a list of directories. It goes to the first directory on the list, looking for all files that appear to contain PostScript fonts; it then adds all those files and fonts to the combined Fontmaps, and starts over.
- If scanning the first FONTPATH directory doesn't produce a file that provides the desired font, it adds the next directory on the FONTPATH list, and so on until either the font is defined successfully or the list is exhausted.
- Finally, if all else fails, it will try to find a substitute for the font from among the standard 35 fonts.

> Differences between search path and font path
> Search path |  | Font path
> `-I` switch |  | `-sFONTPATH=` switch
> `GS_LIB` and `GS_LIB_DEFAULT` environment variables |  | `GS_FONTPATH` environment variable
> Consulted first |  | Consulted only if search path and `FontResourceDir` don't provide the file.
> Font-name-to-file-name mapping given in Fontmap files; aliases are possible, and there need not be any relation between the font name in the Fontmap and the `FontName` in the file. |  | Font-name-to-file-name mapping is implicit -- the `FontName` in the file is used. Aliases are not possible.
> Only fonts and files named in Fontmap are used. |  | Every Type 1 font file in each directory is available; if TrueType fonts are supported (the `ttfont.dev` feature was included when the executable was built), they are also available.

If you are using one of the following types of computer, you may wish to set the environment variable `GS_FONTPATH` to the value indicated so that Ghostscript will automatically acquire all the installed Type 1 (and, if supported, TrueType) fonts (but see below for notes on systems marked with "*"):

> Suggested `GS_FONTPATH` for different systems
> |  | System type |  | `GS_FONTPATH`
> |  | Digital Unix |  | `/usr/lib/X11/fonts/Type1Adobe`
> |  | Ultrix |  | `/usr/lib/DPS/outline/decwin`
> |  | HP-UX 9 |  | `/usr/lib/X11/fonts/type1.st/typefaces`
> |  | IBM AIX |  | `/usr/lpp/DPS/fonts/outlines /usr/lpp/X11/lib/X11/fonts/Type1 /usr/lpp/X11/lib/X11/fonts/Type1/DPS`
> |  | NeXT |  | `/NextLibrary/Fonts/outline`
> * |  | SGI IRIX |  | `/usr/lib/DPS/outline/base /usr/lib/X11/fonts/Type1`
> |  | SunOS 4.x (NeWSprint only) |  | `newsprint_2.5/SUNWsteNP/reloc/$BASEDIR/NeWSprint/ small_openwin/lib/fonts`
> ** |  | SunOS 4.x |  | `/usr/openwin/lib/X11/fonts/Type1/outline`
> ** |  | Solaris 2.x |  | `/usr/openwin/lib/X11/fonts/Type1/outline`
> |  | VMS |  | `SYS$COMMON:[SYSFONT.XDPS.OUTLINE]`

> * On SGI IRIX systems, you must use `Fontmap.SGI` in place of `Fontmap` or `Fontmap.GS`, because otherwise the entries in `Fontmap` will take precedence over the fonts in the FONTPATH directories.

> ** On Solaris systems simply setting `GS_FONTPATH` or using `-sFONTPATH=` may not work, because for some reason some versions of Ghostscript can't seem to find any of the Type1 fonts in `/usr/openwin/lib/X11/fonts/Type1/outline`. (It says: "15 files, 15 scanned, 0 new fonts". We think this problem has been fixed in Ghostscript version 6.0, but we aren't sure because we've never been able to reproduce it.) See `Fontmap.Sol` instead. Also, on Solaris 2.x it's probably not worth your while to add Sun's fonts to your font path and Fontmap. The fonts Sun distributes on Solaris 2.x in the directories

> > `/usr/openwin/lib/X11/fonts/Type1
> > /usr/openwin/lib/X11/fonts/Type1/outline`

> are already represented among the ones distributed as part of Ghostscript; and on some test files, Sun's fonts have been shown to cause incorrect displays with Ghostscript.

These paths may not be exactly right for your installation; if the indicated directory doesn't contain files whose names are familiar font names like Courier and Helvetica, you may wish to ask your system administrator where to find these fonts.

Adobe Acrobat comes with a set of fourteen Type 1 fonts, on Unix typically in a directory called ...`/Acrobat3/Fonts`. There is no particular reason to use these instead of the corresponding fonts in the Ghostscript distribution (which are of just as good quality), except to save about a megabyte of disk space, but the installation documentation explains how to do it on Unix and on DOS (where you can also use Adobe Type Manager fonts).

## Temporary files

> Where Ghostscript puts temporary files
> Platform |  | Filename |  | Location
> DOS and OpenVMS |  | `_temp_`XX.XXX |  | Current directory
> OS/2 |  | `gs`XXXXXX |  | Current directory
> Unix |  | `gs_`XXXXX |  | `/tmp`

You can change in which directory Ghostscript creates temporary files by setting the `TMPDIR` or `TEMP` environment variable to the name of the directory you want used. Ghostscript currently doesn't do a very good job of deleting temporary files if it exits because of an error; you may have to delete them manually from time to time.

# Summary of environment variables

`GS`, `GSC` (MS Windows only)
  Specify the names of the Ghostscript executables. `GS` brings up a new typein window and possibly a graphics window; `GSC` uses the DOS console. If these are not set, `GS` defaults to `gswin32`, and `GSC` defaults to `gswin32c`.

`GS_DEVICE`
  Defines the default output device.

`GS_FONTPATH`
  Specifies a list of directories to scan for fonts if a font requested can't be found anywhere on the search path.

`GS_LIB`
  Provides a search path for initialization files and fonts.

`GS_OPTIONS`
  Defines a list of command-line arguments to be processed before the ones actually specified on the command line. For example, setting `GS_DEVICE` to XYZ is equivalent to setting `GS_OPTIONS` to `-sDEVICE=XYZ`. The contents of `GS_OPTIONS` are not limited to switches; they may include actual file names or even "@file" arguments.

`TEMP`, `TMPDIR`
  Defines a directory name for temporary files. If both `TEMP` and `TMPDIR` are defined, `TMPDIR` takes precedence.

# Using Ghostscript with PDF files

Ghostscript is normally built (except on 16-bit DOS platforms) to interpret both PostScript and PDF files, examining each file to determine automatically whether its contents are PDF or PostScript. All the normal switches and procedures for interpreting PostScript files also apply to PDF files, with a few exceptions. In addition, the `pdf2ps` utility uses Ghostscript to convert PDF to (Level 2) PostScript.

## PDF files from standard input

Using the "`-`" or "`-_`" switch you can provide PDF input from a file, but not from a pipe, because the PDF language, unlike the PostScript language, inherently requires random access to the file, while a pipe is always sequential. That is,

> `gs -_ < somefile.pdf` |  | (is permissible)
> {some program producing PDF} `| gs -_` |  | (is not permissible)

## Switches for PDF files

`-dFirstPage=`pagenumber
  Begins interpreting on the designated page of the document.

`-dLastPage=`pagenumber
  Stops interpreting after the designated page of the document.

`-dPrinted`
`-dPrinted=false`
  Determines whether the file should be displayed or printed using the "screen" or "printer" options for annotations and images. With `-dPrinted`, the output will use the file's "print" options; with `-dPrinted=false`, the output will use the file's "screen" options. If neither of these is specified, the output will use the screen options for any output device that doesn't have an `OutputFile` parameter, and the printer options for devices that do have this parameter.

`-sPDFPassword=`password
  Sets the user or owner password to be used in decoding encrypted PDF files.

## Problems interpreting a PDF file

Occasionally you may try to read or print a `*.pdf` file that Ghostscript doesn't recognize as PDF, even though the same file can be opened and interpreted by an Adobe Acrobat viewer. This can happen when, for instance, a PDF file produced on a Macintosh is carelessly moved to another kind of system, leaving now-useless Macintosh-specific data before the standard header. Ghostscript can't read these files because they don't conform to the PDF standard, Adobe's "Portable Document Format Reference Manual", version 1.2, which states:

> The first line of a PDF file specifies the version number of the PDF specification to which the file adheres.... [T]he first line of a 1.2-conforming PDF file should be `%PDF-1.2`.

However, in an appendix the manual also says that Adobe

> Acrobat viewers are very liberal in their check for a valid PDF header. All viewers allow the header to appear anywhere in the first 1,000 bytes of the file.

Ghostscript doesn't do this: it expects PDF files to conform to the standard, because that's how it recognizes them among other formats it handles, unlike Acrobat viewers which need deal only with PDF and can therefore afford to be more liberal with PDF. So if you encounter a file with useless characters before the header and you want to use it with Ghostscript, you can fix it by stripping the extra characters from before the standard header. The file should begin with exactly the characters

> `%PDF`

PDF files are binary, not text, so be careful to edit the file as a binary, not as text. On Unix, after determining the length of the useless prefix string, which you can do with `od`, you can use `tail` to strip them off. For instance:

> `od -c Macintosh.pdf | more` ;# shows that `%PDF` occurs after 128 characters
> `tail +128c Macintosh.pdf >Legal.pdf`

On PCs and other systems you can use the `hexl` program distributed with GNU emacs to convert the PDF file to editable text form. After editing, `hexl` can convert the text form back to binary.

# Notes on specific platforms

## Unix

The Ghostscript distribution includes some Unix shell scripts to use with Ghostscript in different environments. These are all user-contributed code, so if you have questions, please contact the user identified in the file, not Aladdin Enterprises or artofcode LLC.

`pv.sh`
  Preview a specified page of a `dvi` file in an X window

`sysvlp.sh`
  System V 3.2 lp interface for parallel printer

`pj-gs.sh`
  Printing on an H-P PaintJet under HP-UX

`unix-lpr.sh`
  Queue filter for `lpr` under Unix; its documentation is intended for system administrators

`lprsetup.sh`
  Setup for `unix-lpr.sh`

## VMS

- To be able to specify switches and file names when invoking the interpreter, define `gs` as a foreign command:

  > `$ gs == "$`disk`:[`directory`]gs.exe`"

  where the "disk" and "directory" specify where the Ghostscript executable is located. For instance,

  > `$ gs == "$dua1:[ghostscript]gs.exe"`

- On VMS systems, the last character of each "directory" name indicates what sort of entity the "directory" refers to. If the "directory" name ends with a colon "`:`", it is taken to refer to a logical device, for instance

  > `$ define ghostscript_device dua1:[ghostscript_510]
  > $ define gs_lib ghostscript_device:`

  If the "directory" name ends with a closing square bracket "`]`", it is taken to refer to a real directory, for instance

  > `$ define gs_lib dua1:[ghostscript]`

- Defining the logical `GS_LIB`

  > `$ define gs_lib` disk`:[`directory`]`

  allows Ghostscript to find its initialization files in the Ghostscript directory even if that's not where the executable resides.

- Although VMS DCL itself converts unquoted parameters to upper case, C programs such as Ghostscript receive their parameters through the C runtime library, which forces all unquoted command-line parameters to lower case. That is, with the command

  > `$ gs -Isys$login:`

  Ghostscript sees the switch as `-isys$login`, which doesn't work. To preserve the case of switches, quote them like this:

  > `$ gs "-Isys$login:"`

- If you write printer output to a file with `-sOutputFile=` and then want to print the file later, use "`PRINT/PASSALL`".

- PDF files (or PostScript files that use the `setfileposition` operator) must be "stream LF" type files to work properly on VMS systems. (Note: This definitely matters if Ghostscript was compiled with DEC C; we are not sure of the situation if you use `gcc`.) Because of this, if you transfer files by FTP, you probably need to do one of these two things after the transfer:
  1. If the FTP transfer was in text (ASCII) mode:

     > `$ convert/fdl=streamlf.fdl` input-file output-file

     where the contents of the file `STREAMLF.FDL` are

     >     FILE
     >             ORGANIZATION            sequential

     >     RECORD
     >             BLOCK_SPAN              yes
     >             CARRIAGE_CONTROL        carriage_return
     >             FORMAT                  stream_lf

  2. If the FTP transfer was in binary mode:

     > `$ set file/attribute=(rfm:stmlf)`

### Using X Windows on VMS

If you are using on an X Windows display, you can set it up with the node name and network transport, for instance

> `$ set display/create/node="doof.city.com"/transport=tcpip`

and then run Ghostscript by typing `gs` at the command line.

## MS Windows

You must add gs\`bin` and gs\`lib` to the `PATH`, where gs is the top-level Ghostscript directory.

When passing options to ghostcript through a batch file wrapper such as `ps2pdf.bat` you need to substitute '#' for '=' as the separator between options and their arguments. For example:

>     ps2pdf -sPAPERSIZE#a4 file.ps file.pdf

Ghostscript treats '#' the same internally, and the '=' is mangled by the command shell.

## MS-DOS

You must add gs\`bin` and gs\`lib` to the `PATH`, where gs is the top-level Ghostscript directory.

- Ghostscript supports many SuperVGA displays directly, most of them with more than 16 colors. The complete list is in the file `devs.mak`, part of Ghostscript's source code.
- Some applications, such as Microsoft Word, require a prologue in front of the PostScript files they produce. In the case of MS Word, this prologue is one of the *.ini files Microsoft includes with Word. Other applications may require other prologues. You may specify a prologue on the Ghostscript command line, for instance

  > `gs386 prologue.ini myfile.ps`

- If you have a SuperVGA display that supports a 16-color mode with 800x600 pixels and you know the display mode number for this mode, you can select it by using the command line switches

  > `-sDEVICE=svga16 -dDisplayMode=`NNN

  where NNN is the display mode number in decimal. Here are modes for some popular display chipsets; the ones that use the default value are marked "*". If your card's chipset doesn't appear on this list, or if you try the value here and it doesn't work, please send the name of the chipset and its correct display mode to <bug-gs@aladdin.com> to include in future releases.

  > Display modes for PC display chipsets
  > | Chipset |  | Decimal |  | Hex
  > | Acumos AVGA2, AVGA3 |  | 88 |  | `0x58`
  > | Advance Logic AL2101 |  | 43 |  | `0x2B`
  > | Ahead V5000 |  | 113 |  | `0x71`
  > | ATI VGAWONDER, Graphics Ultra etc. |  | 84 |  | `0x54`
  > | Chips and Technologies |  | 106 |  | `0x6A`
  > | Cirrus Logic CL-GD 500/600 |  | 100 |  | `0x64`
  > | Cirrus Logic GD 5422 |  | 88 |  | `0x58`
  > | Compaq VGA |  | 89 |  | `0x59`
  > | CTI |  | 106 |  | `0x6A`
  > * | Genoa 5xxx, Sigma VGA |  | 41 |  | `0x29`
  > | Genoa 6xxx |  | 106 |  | `0x6A`
  > | MXIC MX 68010 |  | 85 |  | `0x55`
  > | NCR 77C22 |  | 88 |  | `0x58`
  > | OAK Technologies OTI-067, OTI-077, OTI037C |  | 82 |  | `0x52`
  > | OAK Technologies OTI037C w/ NEL BIOS |  | 91 |  | `0x5B`
  > * | Orchid Prodesigner |  | 41 |  | `0x29`
  > | Paradise |  | 88 |  | `0x58`
  > | Poach |  | 106 |  | `0x6A`
  > | Primus |  | 42 |  | `0x2A`
  > | Realtek RT 3106 |  | 31 |  | `0x1F`
  > | Tecmar |  | 22 |  | `0x16`
  > | Trident 8900 |  | 91 |  | `0x5B`
  > * | Tseng ET-3000, ET-4000 |  | 41 |  | `0x29`
  > * | VEGA |  | 41 |  | `0x29`
  > | Video 7 SVGA |  | 98 |  | `0x62`
  > | WD90C11 |  | 92 |  | `0x5C`
  > | Western Digital |  | 88 |  | `0x58`

Note that when passing arguments to batch files (as above) and also with the DOS executable `gs386.exe` build with the Watcom C/C++ compiler, you must use '`#`' rather than '`=`' between a command line switch and its argument, because of a strange design decision in the Wacom run-time library.

## X Windows

Ghostscript looks for the following resources under the program name `ghostscript` and class name `Ghostscript`; the ones marked "**" are calculated from display metrics:

> X Windows resources
> Name |  | Class |  | Default
> `background` |  | `Background` |  | `white`
> `foreground` |  | `Foreground` |  | `black`
> `borderColor` |  | `BorderColor` |  | `black`
> `borderWidth` |  | `BorderWidth` |  | `1`
> `geometry` |  | `Geometry` |  | `NULL`
> `xResolution` |  | `Resolution` |  | **
> `yResolution` |  | `Resolution` |  | **
> `useExternalFonts` |  | `UseExternalFonts` |  | `true`
> `useScalableFonts` |  | `UseScalableFonts` |  | `true`
> `logExternalFonts` |  | `LogExternalFonts` |  | `false`
> `externalFontTolerance` |  | `ExternalFontTolerance` |  | `10.0`
> `palette` |  | `Palette` |  | `Color`
> `maxGrayRamp` |  | `MaxGrayRamp` |  | `128`
> `maxRGBRamp` |  | `MaxRGBRamp` |  | `5`
> `maxDynamicColors` |  | `MaxDynamicColors` |  | `256`
> `useBackingPixmap` |  | `UseBackingPixmap` |  | `true`
> `useXPutImage` |  | `UseXPutImage` |  | `true`
> `useXSetTile` |  | `UseXSetTile` |  | `true`
> `regularFonts` |  | `RegularFonts` |  | See "X fonts"
> `symbolFonts` |  | `SymbolFonts` |  | See "X fonts"
> `dingbatFonts` |  | `DingbatFonts` |  | See "X fonts"

### X resources

- To set X resources, put them in a file (such as `~/.Xdefaults` on Unix) in a form like this:

  > `Ghostscript*geometry:` | `` | `595x842-0+0`
  > `Ghostscript*xResolution:` | `` | `72`
  > `Ghostscript*yResolution:` | `` | `72`

  Then merge these resources into the X server's resource database:

  > `xrdb -merge ~/.Xdefaults`

- Ghostscript doesn't look at the default system background and foreground colors; if you want to change the background or foreground color, you must set them explicitly for Ghostscript. This is a deliberate choice, so that PostScript documents will display correctly by default -- with white as white and black as black -- even if text windows use other colors.
- The `geometry` resource affects only window placement.
- Resolution is expressed in pixels per inch (1 inch = 2.54cm).
- The font tolerance gives the largest acceptable difference in height of the screen font, expressed as a percentage of the height of the desired font.
- The `palette` resource can be used to restrict Ghostscript to using a grayscale or monochrome palette.
- `maxRGBRamp` and `maxGrayRamp` control the maximum number of colors that ghostscript allocates ahead of time for the dither cube (ramp). Ghostscript never preallocates more than half the cells in a colormap. `maxDynamicColors` controls the maximum number of colors that Ghostscript will allocate dynamically in the colormap.

### Working around bugs in X servers

The "`use`..." resources exist primarily to work around bugs in X servers.

- Old versions of DEC's X server (DECwindows) have bugs that require setting `useXPutImage` or `useXSetTile` to `false`.
- Some servers do not implement backing pixmaps properly, or do not have enough memory for them. If you get strange behavior or "out of memory" messages, try setting `useBackingPixmap` to `false`.
- Some servers do not implement tiling properly. This appears as broad bands of color where dither patterns should appear. If this happens, try setting `useXSetTile` to `false`.
- Some servers do not implement bitmap or pixmap displaying properly. This may appear as white or black rectangles where characters should appear; or characters may appear in "inverse video" (for instance, white on a black rectangle rather than black on white). If this happens, try setting `useXPutImage` to `false`.

### X fonts

To use native X11 fonts, Ghostscript must map PostScript font names to the XLFD font names. The resources `regularFonts` (fonts available in standard or ISO-Latin-1 encoding), `symbolFonts` (using Symbol encoding), and `dingbatFonts` (using Dingbat encoding) give the name mapping for different encodings. The XLFD font name in the mapping must contain 7 dashes; the X driver adds the additional size and encoding fields to bring the total number of dashes in the font name to 14. See the appendix "X default font mappings" for the full list of default mappings.

Users who switch regularly between different X servers may wish to use the "*" wild card in place of the foundry name (`itc`, `monotype`, `linotype`, `b&h`, or `adobe`); users who do not switch X servers should leave the explicit foundry in the name, since it speeds up access to fonts.

Ghostscript takes advantage of the "HP XLFD Enhancements," if available, to use native X11 fonts for fonts that are anamorphically scaled, rotated, or mirrored. If the changes have been installed to the X or font server, they are automatically used when appropriate.

### Using Ghostscript fonts on X displays

Font files distributed with Ghostscript can be used on X Windows displays. You can find full instructions in the documentation on fonts.

### X device parameters

In addition to the device parameters recognized by all devices, Ghostscript's X driver provides parameters to adjust its performance. Users will rarely need to modify these. Note that these are parameters to be set with the `-d` switch in the command line (e.g., `-dMaxBitmap=10000000`), not resources to be defined in the `~/.Xdefaults` file.

`AlwaysUpdate <boolean>`
  If `true`, the driver updates the screen after each primitive drawing operation; if `false` (the default), the driver uses an intelligent buffered updating algorithm.

`MaxBitmap <integer>`
  If the amount of memory required to hold the pixmap for the window is no more than the value of `MaxBitmap`, the driver will draw to a pixmap in Ghostscript's address space (called a "client-side pixmap") and will copy it to the screen from time to time; if the amount of memory required for the pixmap exceeds the value of `MaxBitmap`, the driver will draw to a server pixmap. Using a client-side pixmap usually provides better performance -- for bitmap images, possibly much better performance -- but since it may require quite a lot of RAM (e.g., about 2.2 Mb for a 24-bit 1024x768 window), the default value of `MaxBitmap` is 0.

`MaxTempPixmap, MaxTempImage, MaxBufferedTotal, MaxBufferedArea, MaxBufferedCount <integer>`
  These control various aspects of the driver's buffering behavior. For details, please consult the source file `gdevx.h`.

## SCO Unix

Because of bugs in the SCO Unix kernel, Ghostscript will not work if you select direct screen output and also allow it to write messages on the console. If you are using direct screen output, redirect Ghostscript's terminal output to a file.

# Switches

Unless otherwise noted, these switches can be used on all platforms.

## General switches

### Input control

`@`filename
  Causes Ghostscript to read filename and treat its contents the same as the command line. (This is intended primarily for getting around DOS's 128-character limit on the length of a command line.) Switches or file names in the file may be separated by any amount of white space (space, tab, line break); there is no limit on the size of the file.

`--` filename arg1 ...
`-+` filename arg1 ...
  Takes the next argument as a file name as usual, but takes all remaining arguments (even if they have the syntactic form of switches) and defines the name `ARGUMENTS` in userdict (not systemdict) as an array of those strings, before running the file. When Ghostscript finishes executing the file, it exits back to the shell.

`-@` filename arg1 ...
  Does the same thing as `--` and `-+`, but expands `@`filename arguments.

`-`
`-_`
  These are not really switches: they tell Ghostscript to read from standard input, which is coming from a file or a pipe, with or without buffering. See "Input from a pipe" above.

`-c` tokens ...
  Interprets arguments as PostScript code up to the next argument that begins with "`-`" followed by a non-digit, or with "`@`". For example, if the file `quit.ps` contains just the word "`quit`", then `-c quit` on the command line is equivalent to `quit.ps` there. Each argument must be exactly one token, as defined by the `token` operator.

`-f`
  Interprets following non-switch arguments as file names to be executed using the normal `run` command. Since this is the default behavior, `-f` is useful only for terminating the list of tokens for the `-c` switch.

`-f` filename
  Execute the given file, even if its name begins with a "`-`" or "`@`".

### File searching

Note that by "library files" here we mean all the files identified using the search rule under "How Ghostscript finds files" above: Ghostscript's own initialization files, fonts, and files named on the command line.

`-I` directories
  Adds the designated list of directories at the head of the search path for library files.

`-P`
  Makes Ghostscript look first in the current directory for library files. This is currently the default.

`-P-`
  Makes Ghostscript not look first in the current directory for library files (unless, of course, the first explicitly supplied directory is "`.`").

### Setting parameters

`-D` name
`-d` name
  Define a name in systemdict with value=true.

`-D` name`=`token
`-d` name`=`token
  Define a name in systemdict with the given definition. The token must be exactly one token (as defined by the `token` operator) and must not contain any whitespace. If the token is a non-literal name, it must be true, false, or null.

`-S` name`=`string
`-s` name`=`string
  Define a name in systemdict with a given string as value. This is different from `-d`. For example, `-dXYZ=35` on the command line is equivalent to the program fragment

  > `/XYZ 35 def`

  whereas `-sXYZ=35` is equivalent to

  > `/XYZ (35) def`

`-u` name
  Un-define a name, cancelling `-d` or `-s`.

Note that the initialization file `gs_init.ps` makes `systemdict` read-only, so the values of names defined with `-D`, `-d`, `-S`, and `-s` cannot be changed -- although, of course, they can be superseded by definitions in `userdict` or other dictionaries. However, device parameters set this way (`PageSize`, `Margins`, etc.) are not read-only, and can be changed by code in PostScript files.

`-g` number1 `x` number2
  Equivalent to `-dDEVICEWIDTH=`number1 and `-dDEVICEHEIGHT=`number2, specifying the device width and height in pixels for the benefit of devices such as X11 windows and VESA displays that require (or allow) you to specify width and height. Note that this causes documents of other sizes to be clipped, not scaled: see `-dFIXEDMEDIA` below.

`-r` number (same as `-r` number `x` number)
`-r` number1 `x` number2
  Equivalent to `-dDEVICEXRESOLUTION=`number1 and `-dDEVICEYRESOLUTION=`number2, specifying the device horizontal and vertical resolution in pixels per inch for the benefit of devices such as printers that support multiple X and Y resolutions.

### Suppress messages

`-q`
  Quiet startup: suppress normal startup messages, and also do the equivalent of `-dQUIET`.

## Parameter switches (`-d` and `-s`)

As noted above, `-d` and `-s` define initial values for PostScript names. Some of these names are parameters that control the interpreter or the graphics engine. You can also use `-d` or `-s` to define a value for any device parameter of the initial device (the one defined with `-sDEVICE=`, or the default device if this switch is not used). For example, since the `ppmraw` device has a numeric `GrayValues` parameter that controls the number of bits per component, `-sDEVICE=ppmraw -dGrayValues=16` will make this the default device and set the number of bits per component to 4 (log2(16)).

### Rendering parameters

`-dCOLORSCREEN
-dCOLORSCREEN=0
-dCOLORSCREEN=false`
  On high-resolution devices (at least 150 dpi resolution, or `-dDITHERPPI` specified), `-dCOLORSCREEN` forces the use of separate halftone screens with different angles for CMYK or RGB if halftones are needed (this produces the best-quality output); `-dCOLORSCREEN=0` uses separate screens with the same frequency and angle; `-dCOLORSCREEN=false` forces the use of a single binary screen. The default if `COLORSCREEN` is not specified is to use separate screens with different angles if the device has fewer than 5 bits per color, and a single binary screen (which is never actually used under normal circumstances) on all other devices.

`-dDITHERPPI=`lpi
  Forces all devices to be considered high-resolution, and forces use of a halftone screen or screens with lpi lines per inch, disregarding the actual device resolution. Reasonable values for lpi are N/5 to N/20, where N is the resolution in dots per inch.

`-dDOINTERPOLATE`
  Turns on image interpolation for all images, improving image quality for scaled images at the expense of speed. Note that `-dNOINTERPOLATE` overrides `-dDOINTERPOLATE` if both are specified.

`-dNOCIE`
  Substitutes `DeviceGray` and `DeviceRGB` for CIEBasedA and CIEBasedABC color spaces respectively. Useful only on very slow systems where color accuracy is less important.

`-dNOINTERPOLATE`
  Turns off image interpolation, improving performance on interpolated images at the expense of image quality. `-dNOINTERPOLATE` overrides `-dDOINTERPOLATE`.

### Page parameters

`-dFIXEDMEDIA`
  Causes the media size to be fixed after initialization, forcing pages of other sizes or orientations to be clipped. This may be useful when printing documents on a printer that can handle their requested paper size but whose default is some other size. Note that `-g` automatically sets `-dFIXEDMEDIA`, but `-sPAPERSIZE=` does not.

`-dFIXEDRESOLUTION`
  Causes the media resolution to be fixed similarly. `-r` automatically sets `-dFIXEDRESOLUTION`.

`-dORIENT1=true
-dORIENT1=false`
  Defines the meaning of the 0 and 1 orientation values for the setpage[params] compatibility operators. The default value of `ORIENT1` is true (set in `gs_init.ps`), which is the correct value for most files that use setpage[params] at all, namely, files produced by badly designed applications that "know" that the output will be printed on certain roll-media printers: these applications use 0 to mean landscape and 1 to mean portrait. `-dORIENT1=false` declares that 0 means portrait and 1 means landscape, which is the convention used by a smaller number of files produced by properly written applications.

`-dDEVICEWIDTHPOINTS=`w
`-dDEVICEHEIGHTPOINTS=`h
  Sets the initial page width to w or initial page height to h respectively, specified in 1/72" units.

### Font-related parameters

`-dDISKFONTS`
  Causes individual character outlines to be loaded from the disk the first time they are encountered. (Normally Ghostscript loads all the character outlines when it loads a font.) This may allow loading more fonts into memory at the expense of slower rendering. `DISKFONTS` is effective only if the diskfont feature was built into the executable; otherwise it is ignored.

`-dLOCALFONTS`
  Causes Type 1 fonts to be loaded into the current VM -- normally local VM -- instead of always being loaded into global VM. Useful only for compatibility with Adobe printers for loading some obsolete fonts.

`-dNOFONTMAP`
  Suppresses the normal loading of the Fontmap file. This may be useful in environments without a file system.

`-dNOFONTPATH`
  Suppresses consultation of `GS_FONTPATH`. This may be useful for debugging.

`-dNOPLATFONTS`
  Disables the use of fonts supplied by the underlying platform (X Windows or Microsoft Windows). This may be needed if the platform fonts look undesirably different from the scalable fonts.

`-sFONTMAP=`filename1`;`filename2`;`...
  Specifies alternate name or names for the Fontmap file. Note that the names are separated by "`:`" on Unix systems, by "`;`" on DOS or MS Windows systems, and by "`,`" on VMS systems, just as for search paths.

`-sFONTPATH=`dir1`;`dir2`;`...
  Specifies a list of directories that will be scanned when looking for fonts not found on the search path, overriding the environment variable `GS_FONTPATH`.

`-sSUBSTFONT=`fontname
  Causes the given font to be substituted for all unknown fonts, instead of using the normal intelligent substitution algorithm. Also, in this case, the font returned by `findfont` is the actual font named "fontname", not a copy of the font with the `FontName` changed to the requested one.

### Interaction-related parameters

`-dBATCH`
  Causes Ghostscript to exit after processing all files named on the command line, rather than going into an interactive loop reading PostScript commands. Equivalent to putting -c quit at the end of the command line.

`-dNOPAGEPROMPT`
  Disables only the prompt, but not the pause, at the end of each page. This may be useful on PC displays that get confused if a program attempts to write text to the console while the display is in a graphics mode.

`-dNOPAUSE`
  Disables the prompt and pause at the end of each page. Normally one should use this (along with `-dBATCH`) when producing output on a printer or to a file; it also may be desirable for applications where another program is "driving" Ghostscript.

`-dNOPROMPT`
  Disables the prompt printed by Ghostscript when it expects interactive input, as well as the end-of-page prompt (`-dNOPAGEPROMPT`); also disables the implicit `flushpage` that normally occurs each time Ghostscript asks for more input. This allows piping input directly into Ghostscript, as long as the data doesn't refer to `currentfile`.

`-dQUIET`
  Suppresses routine information comments on standard output. This is currently necessary when redirecting device output to standard output.

`-dSHORTERRORS`
  Makes certain error and information messages more Adobe-compatible.

`-dTTYPAUSE`
  Causes Ghostscript to read a character from `/dev/tty`, rather than standard input, at the end of each page. This may be useful if input is coming from a pipe. Note that `-dTTYPAUSE` overrides `-dNOPAUSE`.

### Device and output selection parameters

`-dNODISPLAY`
  Initializes Ghostscript with a null device (a device that discards the output image) rather than the default device or the device selected with `-sDEVICE=`. This is usually useful only when running PostScript code whose purpose is to compute something rather than to produce an output image; for instance, when converting PostScript to PDF.

`-sDEVICE=`device
  Selects an alternate initial output device.

`-sOutputFile=`filename
  Selects an alternate output file (or pipe) for the initial output device, as described above.

### Other parameters

`-dDELAYBIND`
  Causes `bind` to remember all its invocations, but not actually execute them until the `.bindnow` procedure is called. Useful only for certain specialized packages like `pstotext` that redefine operators.

`-dNOBIND`
  Disables the `bind` operator. Useful only for debugging.

`-dNOCACHE`
  Disables character caching. Useful only for debugging.

`-dNOGC`
  Suppresses the initial automatic enabling of the garbage collector in Level 2 systems. (The `vmreclaim` operator is not disabled.) Useful only for debugging.

`-dNOSAFER` (equivalent to `-dDELAYSAFER`).
  This flag disables SAFER mode until the `.setsafe` procedure is run. This is intended for clients or scripts that cannot operate in SAFER mode. If Ghostscript is started with `-dNOSAFER` or `-dDELAYSAFER`, PostScript programs are allowed to read, write, rename or delete any files in the system that are not protected by operating system permissions.

  This mode should be used with caution, and `.setsafe` should be run prior to running any PostScript file with unknown contents.

`-dSAFER`
  Disables the `deletefile` and `renamefile` operators, and the ability to open piped commands (`%pipe%`cmd) at all. Only `%stdout` and `%stderr` can be opened for writing.

  This mode also sets the .LockSafetyParams parameter of the default device, or the device specified with the `-sDEVICE=` switch to protect against programs that attempt to write to files using the OutputFile device parameter. Note that since the device parameters specified on the command line (including OutputFile) are set prior to SAFER mode, the `-sOutputFile=...` on the command line is unrestricted.

  `SAFER` mode also prevents changing the /GenericResourceDir, /FontResourceDir and either the /SystemParamsPassword or the /StartJobPassword.

  Note: While SAFER mode is not the default, in a subsequent release of Ghostscript, SAFER mode will be the default thus scripts or programs that need to open files or set restricted parameters will require the `-dNOSAFER` command line option.

  When running -dNOSAFER it is possible to perform a `save`, followed by `.setsafe`, execute a file or procedure in SAFER mode, then use `restore` to return to NOSAFER mode. In order to prevent the save object from being restored by the foreign file or procedure, the .runandhide operator should be used to hide the save object from the restricted procedure.

`-dPARANOIDSAFER`
  Disables reading of files other than `%stdin`, those given as a command line argument, or those contained on one of the paths given by LIBPATH and FONTPATH and specified by the system params /FontResourceDir and /GenericResourceDir.

  `-dPARANOIDSAFER` implies `-dSAFER` so if `-dPARANOIDSAFER` is given on the command line, `-dSAFER` is optional.

`-dSTRICT`
  Disables as many Ghostscript extensions as feasible, to be more helpful in debugging applications that produce output for Adobe and other RIPs.

`-dWRITESYSTEMDICT`
  Leaves `systemdict` writable. This is necessary when running special utility programs such as `font2c` and `pcharstr`, which must bypass normal PostScript access protection.

# Improving performance

Ghostscript attempts to find an optimum balance between speed and memory consumption, but there are some cases in which you may get a very large speedup by telling Ghostscript to use more memory.

- If you are using X Windows, setting the `-dMaxBitmap=` parameter described above may dramatically improve performance on files that have a lot of bitmap images.
- If you are using Chinese, Japanese, or other fonts with very large character sets, adding the following sequence of switches before the first file name may dramatically improve performance at the cost of an additional 2-3 Mb of memory: `-c 3000000 setvmthreshold -f`.

# Debugging

The information here describing the debugging switches is probably interesting only to developers. The `-Z` switch applies only if the interpreter was built for a debugging configuration. In the table below, the first column is a debugging switch, the second is an equivalent switch (if any) and the third is its usage.

Switches used in debugging
Switch |  | Equivalent |  |
`-A` |  | `-Z@` |  | Fill empty storage with a distinctive bit pattern for debugging
`-A-` |  | `-Z-@` |  | Turn off `-A`
`-B` size |  |  |  | Run all subsequent files named on the command line (except for `-F`) through the run_string interface, using a buffer of size bytes
`-B-` |  |  |  | Turn off `-B`: run subsequent files (except for `-F`) directly in the normal way
`-E` |  | `-Z#` |  | Turn on tracing of error returns from operators
`-E-` |  | `-Z-#` |  | Turn off `-E`
`-F` file |  |  |  | Execute the file with `-B1` temporarily in effect
`-K` n |  |  |  | Limit the total amount of memory that the interpreter can have allocated at any one time to nK bytes. n is a positive decimal integer.
`-M` n |  |  |  | Force the interpreter's allocator to acquire additional memory in units of nK bytes, rather than the default (currently 20K on DOS systems, 50K on Unix). n is a positive decimal integer, on DOS systems no greater than 63.
`-N` n |  |  |  | Allocate space for nK names, rather than the default (normally 64K). n may be greater than 64 only if `EXTEND_NAMES` was defined when the interpreter was compiled .
`-Z` xxx `-Z-`xxx |  |  |  | Turn debugging printout on (off). Each of the xxx characters selects an option. Case is significant: "a" and "A" have different meanings. `0` garbage collector, minimal detail `1` type 1 and type 42 font interpreter `2` curve subdivider/rasterizer `3` curve subdivider/rasterizer, detail `4` garbage collector (strings) `5` garbage collector (strings, detail) `6` garbage collector (chunks, roots) `7` garbage collector (objects) `8` garbage collector (refs) `9` garbage collector (pointers) `a` allocator (large blocks only) `A` allocator (all calls) `b` bitmap image processor `B` bitmap images, detail `c` color/halftone mapper `d` dictionary put/undef `D` dictionary lookups `e` external (OS-related) calls `f` fill algorithm (summary) `F` fill algorithm (detail) `g` gsave/grestore[all] `h` halftone renderer `H` halftones, every pixel `i` interpreter, just names `I` interpreter, everything `j` (Japanese) composite fonts `k` character cache and xfonts `K` character cache, every access `l` command lists, bands `L` command lists, everything `m` makefont and font cache `n` name lookup (new names only) `o` outliner (stroke) `O` stroke detail `p` band list paths `P` all paths `q` clipping `r` arc renderer `s` streams `S` scanner `t` tiling algorithm `u` undo saver (for save/restore), finalization `U` undo saver, more detail `v` alpha/transparency `V` alpha/transparency, more detail `w` compression encoder/decoder `x` transformations `y` Type 1 hints `Y` Type 1 hints, every access `z` trapezoid fill `#` operator error returns `%` externally processed comments `*` image and RasterOp parameters `:` command list and allocator/time summary `~` math functions and Functions `'` contexts, create/destroy `"` contexts, every operation `^` reference counting `_` high-level output `|` (reserved for experimental code) The following switch affects what is printed, but does not select specific items for printing: `/` include file name and line number on all trace output These switches select debugging options other than what should be printed: `$` set unused parts of object references to identifiable garbage values `+` use minimum-size stack blocks `,` don't use path-based banding ``` don't use high-level banded images `.` use small-memory table sizes even on large-memory machines `?` validate pointers before, during and after garbage collection, also before and after save and restore; also make other allocator validity checks `@` fill newly allocated, garbage-collected, and freed storage with a marker (a1, c1, and f1 respectively)

# Appendix: Paper sizes known to Ghostscript

The paper sizes known to Ghostscript are defined at the beginning of the initialization file `gs_statd.ps`; see the comments there for more details about the definitions. The table here lists them by name and size. `gs_statd.ps` defines their sizes exactly in points, and the dimensions in inches (at 72 points per inch) and centimeters shown in the table are derived from those, rounded to the nearest 0.1 unit. A guide to international paper sizes can be found at

> http://www.twics.com/~eds/papersize.html

Paper sizes known to Ghostscript
U.S. standard
|  | Inches |  | cm |  | Points |  |
Name |  | W | × | H |  | W | × | H |  | W | × | H |  |
11x17 |  | 11.0 |  | 17.0 |  | 27.9 |  | 43.2 |  | 792 |  | 1224 |  | 11×17in portrait
ledger |  | 17.0 |  | 11.0 |  | 43.2 |  | 27.9 |  | 1224 |  | 792 |  | 11×17in landscape
legal |  | 8.5 |  | 14.0 |  | 21.6 |  | 35.6 |  | 612 |  | 1008 |  |
letter |  | 8.5 |  | 11.0 |  | 21.6 |  | 27.9 |  | 612 |  | 792 |  |
lettersmall |  | 8.5 |  | 11.0 |  | 21.6 |  | 27.9 |  | 612 |  | 792 |  |
archE |  | 36.0 |  | 48.0 |  | 91.4 |  | 121.9 |  | 2592 |  | 3456 |  |
archD |  | 24.0 |  | 36.0 |  | 61.0 |  | 91.4 |  | 1728 |  | 2592 |  |
archC |  | 18.0 |  | 24.0 |  | 45.7 |  | 61.0 |  | 1296 |  | 1728 |  |
archB |  | 12.0 |  | 18.0 |  | 30.5 |  | 45.7 |  | 864 |  | 1296 |  |
archA |  | 9.0 |  | 12.0 |  | 22.9 |  | 30.5 |  | 648 |  | 864 |  |
ISO standard
a0 |  | 33.1 |  | 46.8 |  | 84.0 |  | 118.8 |  | 2380 |  | 3368 |  |
a1 |  | 23.4 |  | 33.1 |  | 59.4 |  | 84.0 |  | 1684 |  | 2380 |  |
a2 |  | 16.5 |  | 23.4 |  | 42.0 |  | 59.4 |  | 1190 |  | 1684 |  |
a3 |  | 11.7 |  | 16.5 |  | 29.7 |  | 42.0 |  | 842 |  | 1190 |  |
a4 |  | 8.3 |  | 11.7 |  | 21.0 |  | 29.7 |  | 595 |  | 842 |  |
a4small |  | 8.3 |  | 11.7 |  | 21.0 |  | 29.7 |  | 595 |  | 842 |  |
a5 |  | 5.8 |  | 8.3 |  | 14.9 |  | 21.0 |  | 421 |  | 595 |  |
a6 |  | 4.1 |  | 5.8 |  | 10.5 |  | 14.9 |  | 297 |  | 421 |  |
a7 |  | 2.9 |  | 4.1 |  | 7.4 |  | 10.5 |  | 210 |  | 297 |  |
a8 |  | 2.1 |  | 2.9 |  | 5.2 |  | 7.4 |  | 148 |  | 210 |  |
a9 |  | 1.5 |  | 2.1 |  | 3.7 |  | 5.2 |  | 105 |  | 148 |  |
a10 |  | 1.0 |  | 1.5 |  | 2.6 |  | 3.7 |  | 74 |  | 105 |  |
isob0 |  | 39.4 |  | 55.7 |  | 100.0 |  | 141.4 |  | 2836 |  | 4008 |  |
isob1 |  | 27.8 |  | 39.4 |  | 70.7 |  | 100.0 |  | 2004 |  | 2836 |  |
isob2 |  | 19.7 |  | 27.8 |  | 50.0 |  | 70.7 |  | 1418 |  | 2004 |  |
isob3 |  | 13.9 |  | 19.7 |  | 35.3 |  | 50.0 |  | 1002 |  | 1418 |  |
isob4 |  | 9.8 |  | 13.9 |  | 25.0 |  | 35.3 |  | 709 |  | 1002 |  |
isob5 |  | 7.0 |  | 9.8 |  | 17.7 |  | 25.0 |  | 501 |  | 709 |  |
c0 |  | 36.1 |  | 51.1 |  | 91.7 |  | 129.7 |  | 2600 |  | 3677 |  |
c1 |  | 25.5 |  | 36.1 |  | 64.8 |  | 91.7 |  | 1837 |  | 2600 |  |
c2 |  | 18.0 |  | 25.5 |  | 45.8 |  | 64.8 |  | 1298 |  | 1837 |  |
c3 |  | 12.8 |  | 18.0 |  | 32.4 |  | 45.8 |  | 918 |  | 1298 |  |
c4 |  | 9.0 |  | 12.8 |  | 22.9 |  | 32.4 |  | 649 |  | 918 |  |
c5 |  | 6.4 |  | 9.0 |  | 16.2 |  | 22.9 |  | 459 |  | 649 |  |
c6 |  | 4.5 |  | 6.4 |  | 11.4 |  | 16.2 |  | 323 |  | 459 |  |
JIS standard
jisb0 |  |  |  |  |  | 103.0 |  | 145.6 |  |  |  |  |  |
jisb1 |  |  |  |  |  | 72.8 |  | 103.0 |  |  |  |  |  |
jisb2 |  |  |  |  |  | 51.5 |  | 72.8 |  |  |  |  |  |
jisb3 |  |  |  |  |  | 36.4 |  | 51.5 |  |  |  |  |  |
jisb4 |  |  |  |  |  | 25.7 |  | 36.4 |  |  |  |  |  |
jisb5 |  |  |  |  |  | 18.2 |  | 25.7 |  |  |  |  |  |
jisb6 |  |  |  |  |  | 12.8 |  | 18.2 |  |  |  |  |  |
ISO/JIS switchable
b0 (see * below)
b1 (see * below)
b2 (see * below)
b3 (see * below)
b4 (see * below)
b5 (see * below)
Other
flsa |  | 8.5 |  | 13.0 |  | 21.6 |  | 33.0 |  | 612 |  | 936 |  | U.S. foolscap
flse |  | 8.5 |  | 13.0 |  | 21.6 |  | 33.0 |  | 612 |  | 936 |  | European foolscap
halfletter |  | 5.5 |  | 8.5 |  | 14.0 |  | 21.6 |  | 396 |  | 612 |  |

*Note: Initially the B paper sizes are the ISO sizes, e.g., `b0` is the same as `isob0`. Running the file `lib/jispaper.ps` makes the B paper sizes be the JIS sizes, e.g., `b0` becomes the same as `jisb0`.

# Appendix: X default font mappings

## Standard X servers

### Regular fonts

        AvantGarde-Book:              -Adobe-ITC Avant Garde Gothic-Book-R-Normal--\n\
        AvantGarde-BookOblique:       -Adobe-ITC Avant Garde Gothic-Book-O-Normal--\n\
        AvantGarde-Demi:              -Adobe-ITC Avant Garde Gothic-Demi-R-Normal--\n\
        AvantGarde-DemiOblique:       -Adobe-ITC Avant Garde Gothic-Demi-O-Normal--\n\
        Bookman-Demi:                 -Adobe-ITC Bookman-Demi-R-Normal--\n\
        Bookman-DemiItalic:           -Adobe-ITC Bookman-Demi-I-Normal--\n\
        Bookman-Light:                -Adobe-ITC Bookman-Light-R-Normal--\n\
        Bookman-LightItalic:          -Adobe-ITC Bookman-Light-I-Normal--\n\
        Courier:                      -Adobe-Courier-Medium-R-Normal--\n\
        Courier-Bold:                 -Adobe-Courier-Bold-R-Normal--\n\
        Courier-BoldOblique:          -Adobe-Courier-Bold-O-Normal--\n\
        Courier-Oblique:              -Adobe-Courier-Medium-O-Normal--\n\
        Helvetica:                    -Adobe-Helvetica-Medium-R-Normal--\n\
        Helvetica-Bold:               -Adobe-Helvetica-Bold-R-Normal--\n\
        Helvetica-BoldOblique:        -Adobe-Helvetica-Bold-O-Normal--\n\
        Helvetica-Narrow:             -Adobe-Helvetica-Medium-R-Narrow--\n\
        Helvetica-Narrow-Bold:        -Adobe-Helvetica-Bold-R-Narrow--\n\
        Helvetica-Narrow-BoldOblique: -Adobe-Helvetica-Bold-O-Narrow--\n\
        Helvetica-Narrow-Oblique:     -Adobe-Helvetica-Medium-O-Narrow--\n\
        Helvetica-Oblique:            -Adobe-Helvetica-Medium-O-Normal--\n\
        NewCenturySchlbk-Bold:        -Adobe-New Century Schoolbook-Bold-R-Normal--\n\
        NewCenturySchlbk-BoldItalic:  -Adobe-New Century Schoolbook-Bold-I-Normal--\n\
        NewCenturySchlbk-Italic:      -Adobe-New Century Schoolbook-Medium-I-Normal--\n\
        NewCenturySchlbk-Roman:       -Adobe-New Century Schoolbook-Medium-R-Normal--\n\
        Palatino-Bold:                -Adobe-Palatino-Bold-R-Normal--\n\
        Palatino-BoldItalic:          -Adobe-Palatino-Bold-I-Normal--\n\
        Palatino-Italic:              -Adobe-Palatino-Medium-I-Normal--\n\
        Palatino-Roman:               -Adobe-Palatino-Medium-R-Normal--\n\
        Times-Bold:                   -Adobe-Times-Bold-R-Normal--\n\
        Times-BoldItalic:             -Adobe-Times-Bold-I-Normal--\n\
        Times-Italic:                 -Adobe-Times-Medium-I-Normal--\n\
        Times-Roman:                  -Adobe-Times-Medium-R-Normal--\n\
        ZapfChancery-MediumItalic:    -Adobe-ITC Zapf Chancery-Medium-I-Normal--

### Symbol fonts

        Symbol:                       -Adobe-Symbol-Medium-R-Normal--

### Dingbat fonts

        ZapfDingbats:                 -Adobe-ITC Zapf Dingbats-Medium-R-Normal--

## Sun OpenWindows

For Sun's X11/NeWS one can use the OpenWindows scalable fonts instead, which gives good output for any point size. In this environment, the relevant section of the resource file should look like this:

    Ghostscript.regularFonts: \
        AvantGarde-Book:              -itc-avantgarde-book-r-normal-- \n\
        AvantGarde-BookOblique:       -itc-avantgarde-book-o-normal-- \n\
        AvantGarde-Demi:              -itc-avantgarde-demi-r-normal-- \n\
        AvantGarde-DemiOblique:       -itc-avantgarde-demi-o-normal-- \n\
        Bembo:                        -monotype-bembo-medium-r-normal-- \n\
        Bembo-Bold:                   -monotype-bembo-bold-r-normal-- \n\
        Bembo-BoldItalic:             -monotype-bembo-bold-i-normal-- \n\
        Bembo-Italic:                 -monotype-bembo-medium-i-normal-- \n\
        Bookman-Demi:                 -itc-bookman-demi-r-normal-- \n\
        Bookman-DemiItalic:           -itc-bookman-demi-i-normal-- \n\
        Bookman-Light:                -itc-bookman-light-r-normal-- \n\
        Bookman-LightItalic:          -itc-bookman-light-i-normal-- \n\
        Courier:                      -itc-courier-medium-r-normal-- \n\
        Courier-Bold:                 -itc-courier-bold-r-normal-- \n\
        Courier-BoldOblique:          -itc-courier-bold-o-normal-- \n\
        Courier-Oblique:              -itc-courier-medium-o-normal-- \n\
        GillSans:                     -monotype-gill-medium-r-normal-sans- \n\
        GillSans-Bold:                -monotype-gill-bold-r-normal-sans- \n\
        GillSans-BoldItalic:          -monotype-gill-bold-i-normal-sans- \n\
        GillSans-Italic:              -monotype-gill-normal-i-normal-sans- \n\
        Helvetica:                    -linotype-helvetica-medium-r-normal-- \n\
        Helvetica-Bold:               -linotype-helvetica-bold-r-normal-- \n\
        Helvetica-BoldOblique:        -linotype-helvetica-bold-o-normal-- \n\
        Helvetica-Narrow:             -linotype-helvetica-medium-r-narrow-- \n\
        Helvetica-Narrow-Bold:        -linotype-helvetica-bold-r-narrow-- \n\
        Helvetica-Narrow-BoldOblique: -linotype-helvetica-bold-o-narrow-- \n\
        Helvetica-Narrow-Oblique:     -linotype-helvetica-medium-o-narrow-- \n\
        Helvetica-Oblique:            -linotype-helvetica-medium-o-normal-- \n\
        LucidaBright:                 -b&h-lucidabright-medium-r-normal-- \n\
        LucidaBright-Demi:            -b&h-lucidabright-demibold-r-normal-- \n\
        LucidaBright-DemiItalic:      -b&h-lucidabright-demibold-i-normal-- \n\
        LucidaBright-Italic:          -b&h-lucidabright-medium-i-normal-- \n\
        LucidaSans:                   -b&h-lucida-medium-r-normal-sans- \n\
        LucidaSans-Bold:              -b&h-lucida-bold-r-normal-sans- \n\
        LucidaSans-BoldItalic:        -b&h-lucida-bold-i-normal-sans- \n\
        LucidaSans-Italic:            -b&h-lucida-medium-i-normal-sans- \n\
        LucidaSans-Typewriter:        -b&h-lucidatypewriter-medium-r-normal-sans- \n\
        LucidaSans-TypewriterBold:    -b&h-lucidatypewriter-bold-r-normal-sans- \n\
        NewCenturySchlbk-BoldItalic:  -linotype-new century schoolbook-bold-i-normal-- \n\
        NewCenturySchlbk-Bold:        -linotype-new century schoolbook-bold-r-normal-- \n\
        NewCenturySchlbk-Italic:      -linotype-new century schoolbook-medium-i-normal-- \n\
        NewCenturySchlbk-Roman:       -linotype-new century schoolbook-medium-r-normal-- \n\
        Palatino-Bold:                -linotype-palatino-bold-r-normal-- \n\
        Palatino-BoldItalic:          -linotype-palatino-bold-i-normal-- \n\
        Palatino-Italic:              -linotype-palatino-medium-i-normal-- \n\
        Palatino-Roman:               -linotype-palatino-medium-r-normal-- \n\
        Rockwell:                     -monotype-rockwell-medium-r-normal-- \n\
        Rockwell-Bold:                -monotype-rockwell-bold-r-normal-- \n\
        Rockwell-BoldItalic:          -monotype-rockwell-bold-i-normal-- \n\
        Rockwell-Italic:              -monotype-rockwell-medium-i-normal-- \n\
        Times-Bold:                   -linotype-times-bold-r-normal-- \n\
        Times-BoldItalic:             -linotype-times-bold-i-normal-- \n\
        Times-Italic:                 -linotype-times-medium-i-normal-- \n\
        Times-Roman:                  -linotype-times-medium-r-normal-- \n\
        Utopia-Bold:                  -adobe-utopia-bold-r-normal-- \n\
        Utopia-BoldItalic:            -adobe-utopia-bold-i-normal-- \n\
        Utopia-Italic:                -adobe-utopia-regular-i-normal-- \n\
        Utopia-Regular:               -adobe-utopia-regular-r-normal-- \n\
        ZapfChancery-MediumItalic:    -itc-zapfchancery-medium-i-normal-- \n
    Ghostscript.dingbatFonts: \
        ZapfDingbats:                 -itc-zapfdingbats-medium-r-normal--
    Ghostscript.symbolFonts: \
        Symbol:                       --symbol-medium-r-normal--

Copyright © 1996, 2000 Aladdin Enterprises. All rights reserved.

This file is part of GNU Ghostscript. See the GNU General Public License (the "License") for full details of the terms of using, copying, modifying, and redistributing GNU Ghostscript.

GNU Ghostscript version 6.53, 13 February 2002