TeX formats the interspersed text and commands contained in the named files and outputs a typesetter independent file (called DVI, which is short for DeVice Independent). TeX's capabilities and language are described in The TeX book. TeX is normally used with a large body of precompiled macros, and there are several specific formatting systems, such as LaTeX, which require the support of several macro files.

This version of TeX looks at its command line to see what name it was called under. Both initex and virtex are symlinks to the tex executable. When called as initex (or when the --ini option is given) it can be used to precompile macros into a .fmt file. When called as virtex it will use the plain format. When called under any other name, TeX will use that name as the name of the format to use. For example, when called as tex the tex format is used, which is identical to the plain format. The commands defined by the plain format are documented in The TeX book. Other formats that are often available include latex and amstex.

The commands given on the command line to the TeX program are passed to it as the first input line. (But it is often easier to type extended arguments as the first input line, since UNIX shells tend to gobble up or misinterpret TeX's favorite symbols, like backslashes, unless you quote them.) As described in The TeX book, that first line should begin with a filename, a \controlsequence, or a &formatname.

The normal usage is to say

tex paper

This version of TeX can look in the first line of the file paper.tex to see if it begins with the magic sequence %&. If the first line begins with %&format --translate-file tcxname then TeX will use the named format and transation table tcxname to process the source file. Either the format name or the --translate-file specification may be omitted, but not both. This overrides the format selection based on the name by which the program is invoked. The --parse-first-line option or the parse_first_line configuration variable control whether this behaviour is enabled.

The e response to TeX's error prompt causes the system default editor to start up at the current line of the current file. The environment variable TEXEDIT can be used to change the editor used. It may contain a string with "%s" indicating where the filename goes and "%d" indicating where the decimal line number (if any) goes. For example, a TEXEDIT string for emacs can be set with the sh command

TEXEDIT="emacs +%d %s"; export TEXEDIT

A convenient file in the library is null.tex, containing nothing. When TeX can't find a file it thinks you want to input, it keeps asking you for another filename; responding `null' gets you out of the loop if you don't want to input anything. You can also type your EOF character (usually control-D).

--file-line-error-style

Print error messages in the form file:line:error which is similar to the way many compilers format them.

--fmt format

Use format as the name of the format to be used, instead of the name by which TeX was called or a %& line.

--help

Print help message and exit.

--ini

Be initex, for dumping formats; this is implicitly true if the program is called as initex.

--interaction mode

Sets the interaction mode. The mode can be one of batchmode, nonstopmode, scrollmode, and errorstopmode. The meaning of these modes is the same as that of the corresponding \commands.

--ipc

Send DVI output to a socket as well as the usual output file. Whether this option is available is the choice of the installer.

--ipc-start

As --ipc, and starts the server at the other end as well. Whether this option is available is the choice of the installer.

--jobname name

Use name for the job name, instead of deriving it from the name of the input file.

--kpathsea-debug bitmask

Sets path searching debugging flags according to the bitmask. See the Kpathsea manual for details.

--maketex fmt

Enable mktexfmt, where fmt must be one of tex or tfm.

--mltex

Enable MLTeX extensions.

--no-maketex fmt

Disable mktexfmt, where fmt must be one of tex or tfm.

--output-comment string

Use string for the DVI file comment instead of the date.

--parse-first-line

If the first line of the main input file begins with %& parse it to look for a dump name or a --translate-file option.

--progname name

Pretend to be program name. This affects both the format used and the search paths.

--recorder

Enable the filename recorder. This leaves a trace of the files opened for input and output in a file with extension .fls.

--shell-escape

Enable the \write18{command} construct. The command can be any Bourne shell command. This construct is normally disallowed for security reasons.

--translate-file tcxname

Use the tcxname translation table.

--version

Print version information and exit.

One caveat: In most TeX formats, you cannot use ~ in a filename you give directly to TeX, because ~ is an active character, and hence is expanded, not taken as part of the filename. Other programs, such as Metafont, do not have this problem.

TEXMFOUTPUT

Normally, TeX puts its output files in the current directory. If any output file cannot be opened there, it tries to open it in the directory specified in the environment variable TEXMFOUTPUT. There is no default value for that variable. For example, if you say tex paper and the current directory is not writable, if TEXMFOUTPUT has the value /tmp, TeX attempts to create /tmp/paper.log (and /tmp/paper.dvi, if any output is produced.)

TEXINPUTS

Search path for \input and \openin files. This should probably start with ``.'', so that user files are found before system files. An empty path component will be replaced with the paths defined in the texmf.cnf file. For example, set TEXINPUTS to ".:/home/usr/tex:" to prepend the current direcory and ``/home/user/tex'' to the standard search path.

TEXEDIT

Command template for switching to editor. The default, usually vi, is set when TeX is compiled.

texmf.cnf

Configuration file. This contains definitions of search paths as well as other configuration parameters like parse_first_line.

tex.pool

Encoded text of TeX's messages.

texfonts.map

Filename mapping definitions.

*.tfm

Metric files for TeX's fonts.

*.fmt

Predigested TeX format (.fmt) files.

$TEXMFMAIN/tex/plain/base/plain.tex

The basic macro package described in the TeX book.

This version of TeX fails to trap arithmetic overflow when dimensions are added or subtracted. Cases where this occurs are rare, but when it does the generated DVI file will be invalid.