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    76 .\" modified to reference existing Solaris man pages, to add the Solaris

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    78 .\"

    79 .TH TCSH 1 "10 July 2009" "Astron 6.17.00"

    80 .SH NAME

    81 tcsh \- C shell with file name completion and command line editing

    82 .SH SYNOPSIS

    83 .B tcsh \fR[\fB\-bcdefFimnqstvVxX\fR] [\fB\-Dname\fR[\fB=value\fR]] [arg ...]

    84 .br

    85 .B tcsh \-l

    86 .SH DESCRIPTION

    87 \fItcsh\fR is an enhanced but completely compatible version of the Berkeley

    88 UNIX C shell, \fIcsh\fR(1).

    89 It is a command language interpreter usable both as an interactive login

    90 shell and a shell script command processor.

    91 It includes a command-line editor (see \fBThe command-line editor\fR),

    92 programmable word completion (see \fBCompletion and listing\fR),

    93 spelling correction (see \fBSpelling correction\fR),

    94 a history mechanism (see \fBHistory substitution\fR),

    95 job control (see \fBJobs\fR)

    96 and a C-like syntax.

    97 The \fBNEW FEATURES\fR section describes major enhancements of \fItcsh\fR

    98 over \fIcsh\fR(1).

    99 Throughout this manual, features of

   100 \fItcsh\fR not found in most \fIcsh\fR(1) implementations

   101 (specifically, the 4.4BSD \fIcsh\fR)

   102 are labeled with `(+)', and features which are present in \fIcsh\fR(1)

   103 but not usually documented are labeled with `(u)'.

   104 .SS "Argument list processing"

   105 If the first argument (argument 0) to the shell is `\-' then it is a

   106 login shell.  A login shell can be also specified by invoking the shell with

   107 the \fB\-l\fR flag as the only argument.

   108 .PP

   109 The rest of the flag arguments are interpreted as follows:

   110 .TP 4

   111 .B \-b

   112 Forces a ``break'' from option processing, causing any

   113 further shell arguments to be treated as non-option arguments.  The remaining

   114 arguments will not be interpreted as shell options.  This may be used to pass

   115 options to a shell script without confusion or possible subterfuge.  The shell

   116 will not run a set-user ID script without this option.

   117 .TP 4

   118 .B \-c

   119 Commands are read from the following argument (which must be present, and

   120 must be a single argument),

   121 stored in the \fBcommand\fR shell variable for reference, and executed.

   122 Any remaining arguments are placed in the \fBargv\fR shell variable.

   123 .TP 4

   124 .B \-d

   125 The shell loads the directory stack from \fI~/.cshdirs\fR as described under

   126 \fBStartup and shutdown\fR, whether or not it is a login shell. (+)

   127 .TP 4

   128 .B \-D\fIname\fR[=\fIvalue\fR]

   129 Sets the environment variable \fIname\fR to \fIvalue\fR. (Domain/OS only) (+)

   130 .TP 4

   131 .B \-e

   132 The shell exits if any invoked command terminates abnormally or

   133 yields a non-zero exit status.

   134 .TP 4

   135 .B \-f

   136 The shell does not load any resource or startup files, or perform any 

   137 command hashing, and thus starts faster.

   138 .TP 4

   139 .B \-F

   140 The shell uses \fIfork\fR(2) instead of \fIvfork\fR(2) to spawn processes. (+)

   141 .TP 4

   142 .B \-i

   143 The shell is interactive and prompts for its top-level input, even if

   144 it appears to not be a terminal.  Shells are interactive without this option if

   145 their inputs and outputs are terminals.

   146 .TP 4

   147 .B \-l

   148 The shell is a login shell.  Applicable only if \fB\-l\fR is the only

   149 flag specified.

   150 .TP 4

   151 .B \-m

   152 The shell loads \fI~/.tcshrc\fR even if it does not belong to the effective

   153 user.  Newer versions of \fIsu\fR(1M) can pass \fB\-m\fR to the shell. (+)

   154 .TP 4

   155 .B \-n

   156 The shell parses commands but does not execute them.

   157 This aids in debugging shell scripts.

   158 .TP 4

   159 .B \-q

   160 The shell accepts SIGQUIT (see \fBSignal handling\fR) and behaves when

   161 it is used under a debugger.  Job control is disabled. (u)

   162 .TP 4

   163 .B \-s

   164 Command input is taken from the standard input.

   165 .TP 4

   166 .B \-t

   167 The shell reads and executes a single line of input.  A `\\' may be used to

   168 escape the newline at the end of this line and continue onto another line.

   169 .TP 4

   170 .B \-v

   171 Sets the \fBverbose\fR shell variable, so that

   172 command input is echoed after history substitution.

   173 .TP 4

   174 .B \-x

   175 Sets the \fBecho\fR shell variable, so that commands are echoed

   176 immediately before execution.

   177 .TP 4

   178 .B \-V

   179 Sets the \fBverbose\fR shell variable even before executing \fI~/.tcshrc\fR.

   180 .TP 4

   181 .B \-X

   182 Is to \fB\-x\fR as \fB\-V\fR is to \fB\-v\fR.

   183 .TP 4

   184 .B \-\-help

   185 Print a help message on the standard output and exit. (+)

   186 .TP 4

   187 .B \-\-version

   188 Print the version/platform/compilation options on the standard output and exit.

   189 This information is also contained in the \fBversion\fR shell variable. (+)

   190 .PP

   191 After processing of flag arguments, if arguments remain but none of the

   192 \fB\-c\fR, \fB\-i\fR, \fB\-s\fR, or \fB\-t\fR options were given, the first

   193 argument is taken as the name of a file of commands, or ``script'', to

   194 be executed.  The shell opens this file and saves its name for possible

   195 resubstitution by `$0'.  Because many systems use either the standard

   196 version 6 or version 7 shells whose shell scripts are not compatible

   197 with this shell, the shell uses such a `standard' shell to execute a script

   198 whose first character is not a `#', i.e., that does not start with a

   199 comment.

   200 .PP

   201 Remaining arguments are placed in the \fBargv\fR shell variable.

   202 .SS "Startup and shutdown"

   203 A login shell begins by executing commands from the system files

   204 \fI/etc/.cshrc\fR and \fI/etc/.login\fR.

   205 It then executes commands from files in the user's \fBhome\fR directory:

   206 first \fI~/.tcshrc\fR (+)

   207 or, if \fI~/.tcshrc\fR is not found, \fI~/.cshrc\fR,

   208 then \fI~/.history\fR (or the value of the \fBhistfile\fR shell variable),

   209 then \fI~/.login\fR,

   210 and finally \fI~/.cshdirs\fR (or the value of the \fBdirsfile\fR shell variable) (+).

   211 The shell may read \fI/etc/csh.login\fR before instead of after

   212 \fI/etc/.cshrc\fR, and \fI~/.login\fR before instead of after

   213 \fI~/.tcshrc\fR or \fI~/.cshrc\fR and \fI~/.history\fR, if so compiled;

   214 see the \fBversion\fR shell variable. (+)

   215 .PP

   216 Non-login shells read only \fI/etc/.cshrc\fR and \fI~/.tcshrc\fR

   217 or \fI~/.cshrc\fR on startup.

   218 .PP

   219 For examples of startup files, please consult

   220 \fIhttp://tcshrc.sourceforge.net\fR.

   221 .PP

   222 Commands like \fIstty\fR(1) and \fItset\fR(1B),

   223 which need be run only once per login, usually go in one's \fI~/.login\fR file.

   224 Users who need to use the same set of files with both \fIcsh\fR(1) and

   225 \fItcsh\fR can have only a \fI~/.cshrc\fR which checks for the existence of the

   226 \fBtcsh\fR shell variable (q.v.) before using \fItcsh\fR-specific commands,

   227 or can have both a \fI~/.cshrc\fR and a \fI~/.tcshrc\fR which \fIsource\fRs

   228 (see the builtin command) \fI~/.cshrc\fR.

   229 The rest of this manual uses `\fI~/.tcshrc\fR' to mean `\fI~/.tcshrc\fR or,

   230 if \fI~/.tcshrc\fR is not found, \fI~/.cshrc\fR'.

   231 .PP

   232 In the normal case, the shell begins reading commands from the terminal,

   233 prompting with `> '.  (Processing of arguments and the use of the shell to

   234 process files containing command scripts are described later.)

   235 The shell repeatedly reads a line of command input, breaks it into words,

   236 places it on the command history list, parses it and executes each command

   237 in the line.

   238 .PP

   239 One can log out by typing `^D' on an empty line, `logout' or `login' or

   240 via the shell's autologout mechanism (see the \fBautologout\fR shell variable).

   241 When a login shell terminates it sets the \fBlogout\fR shell variable to

   242 `normal' or `automatic' as appropriate, then

   243 executes commands from the files

   244 \fI/etc/csh.logout\fR and \fI~/.logout\fR.  The shell may drop DTR on logout

   245 if so compiled; see the \fBversion\fR shell variable.

   246 .PP

   247 The names of the system login and logout files vary from system to system for

   248 compatibility with different \fIcsh\fR(1) variants; see \fBFILES\fR.

   249 .SS Editing

   250 We first describe \fBThe command-line editor\fR.

   251 The \fBCompletion and listing\fR and \fBSpelling correction\fR sections

   252 describe two sets of functionality that are implemented as editor commands

   253 but which deserve their own treatment.

   254 Finally, \fBEditor commands\fR lists and describes

   255 the editor commands specific to the shell and their default bindings.

   256 .SS "The command-line editor (+)"

   257 Command-line input can be edited using key sequences much like those used in

   258 GNU Emacs or \fIvi\fR(1).

   259 The editor is active only when the \fBedit\fR shell variable is set, which

   260 it is by default in interactive shells.

   261 The \fIbindkey\fR builtin can display and change key bindings.

   262 Emacs-style key bindings are used by default

   263 (unless the shell was compiled otherwise; see the \fBversion\fR shell variable),

   264 but \fIbindkey\fR can change the key bindings to \fIvi\fR-style bindings en masse.

   265 .PP

   266 The shell always binds the arrow keys (as defined in the \fBTERMCAP\fR

   267 environment variable) to

   268 .PP

   269 .PD 0

   270 .RS +4

   271 .TP 8

   272 down

   273 \fIdown-history\fR

   274 .TP 8

   275 up

   276 \fIup-history\fR

   277 .TP 8

   278 left

   279 \fIbackward-char\fR

   280 .TP 8

   281 right

   282 \fIforward-char\fR

   283 .PD

   284 .RE

   285 .PP

   286 unless doing so would alter another single-character binding.

   287 One can set the arrow key escape sequences to the empty string with \fIsettc\fR

   288 to prevent these bindings.

   289 The ANSI/VT100 sequences for arrow keys are always bound.

   290 .PP

   291 Other key bindings are, for the most part, what Emacs and \fIvi\fR(1)

   292 users would expect and can easily be displayed by \fIbindkey\fR, so there

   293 is no need to list them here.  Likewise, \fIbindkey\fR can list the editor

   294 commands with a short description of each.

   295 .PP

   296 Note that editor commands do not have the same notion of a ``word'' as does the

   297 shell.  The editor delimits words with any non-alphanumeric characters not in

   298 the shell variable \fBwordchars\fR, while the shell recognizes only whitespace

   299 and some of the characters with special meanings to it, listed under

   300 \fBLexical structure\fR.

   301 .SS "Completion and listing (+)"

   302 The shell is often able to complete words when given a unique abbreviation.

   303 Type part of a word (for example `ls /usr/lost') and hit the tab key to

   304 run the \fIcomplete-word\fR editor command.

   305 The shell completes the filename `/usr/lost' to `/usr/lost+found/',

   306 replacing the incomplete word with the complete word in the input buffer.

   307 (Note the terminal `/'; completion adds a `/' to the

   308 end of completed directories and a space to the end of other completed words,

   309 to speed typing and provide a visual indicator of successful completion.

   310 The \fBaddsuffix\fR shell variable can be unset to prevent this.)

   311 If no match is found (perhaps `/usr/lost+found' doesn't exist),

   312 the terminal bell rings.

   313 If the word is already complete (perhaps there is a `/usr/lost' on your

   314 system, or perhaps you were thinking too far ahead and typed the whole thing)

   315 a `/' or space is added to the end if it isn't already there.

   316 .PP

   317 Completion works anywhere in the line, not at just the end; completed

   318 text pushes the rest of the line to the right.  Completion in the middle of a word

   319 often results in leftover characters to the right of the cursor that need

   320 to be deleted.

   321 .PP

   322 Commands and variables can be completed in much the same way.

   323 For example, typing `em[tab]' would complete `em' to

   324 `emacs' if \fIemacs\fR were the only command on your system beginning with `em'.

   325 Completion can find a command in any directory in \fBpath\fR or if

   326 given a full pathname.

   327 Typing `echo $ar[tab]' would complete `$ar' to `$argv'

   328 if no other variable began with `ar'.

   329 .PP

   330 The shell parses the input buffer to determine whether the word you want to

   331 complete should be completed as a filename, command or variable.

   332 The first word in the buffer and the first word following

   333 `;', `|', `|&', `&&' or `||' is considered to be a command.

   334 A word beginning with `$' is considered to be a variable.

   335 Anything else is a filename.  An empty line is `completed' as a filename.

   336 .PP

   337 You can list the possible completions of a word at any time by typing `^D'

   338 to run the \fIdelete-char-or-list-or-eof\fR editor command.

   339 The shell lists the possible completions using the \fIls\-F\fR builtin (q.v.)

   340 and reprints the prompt and unfinished command line, for example:

   341 .IP "" 4

   342 > ls /usr/l[^D]

   343 .br

   344 lbin/       lib/        local/      lost+found/

   345 .br

   346 > ls /usr/l

   347 .PP

   348 If the \fBautolist\fR shell variable is set, the shell lists the remaining

   349 choices (if any) whenever completion fails:

   350 .IP "" 4

   351 > set autolist

   352 .br

   353 > nm /usr/lib/libt[tab]

   354 .br

   355 libtermcap.a@ libtermlib.a@

   356 .br

   357 > nm /usr/lib/libterm

   358 .PP

   359 If \fBautolist\fR is set to `ambiguous', choices are listed only when

   360 completion fails and adds no new characters to the word being completed.

   361 .PP

   362 A filename to be completed can contain variables, your own or others' home

   363 directories abbreviated with `~' (see \fBFilename substitution\fR) and

   364 directory stack entries abbreviated with `='

   365 (see \fBDirectory stack substitution\fR).  For example,

   366 .IP "" 4

   367 > ls ~k[^D]

   368 .br

   369 kahn    kas     kellogg

   370 .br

   371 > ls ~ke[tab]

   372 .br

   373 > ls ~kellogg/

   374 .PP

   375 or

   376 .IP "" 4

   377 > set local = /usr/local

   378 .br

   379 > ls $lo[tab]

   380 .br

   381 > ls $local/[^D]

   382 .br

   383 bin/ etc/ lib/ man/ src/

   384 .br

   385 > ls $local/

   386 .PP

   387 Note that variables can also be expanded explicitly with the

   388 \fIexpand-variables\fR editor command.

   389 .PP

   390 \fIdelete-char-or-list-or-eof\fR lists at only the end of the line;

   391 in the middle of a line it deletes the character under the cursor and

   392 on an empty line it logs one out or, if \fBignoreeof\fR is set, does nothing.

   393 `M-^D', bound to the editor command \fIlist-choices\fR, lists completion

   394 possibilities anywhere on a line, and \fIlist-choices\fR (or any one of the

   395 related editor commands that do or don't delete, list and/or log out,

   396 listed under \fIdelete-char-or-list-or-eof\fR) can be bound to `^D' with

   397 the \fIbindkey\fR builtin command if so desired.

   398 .PP

   399 The \fIcomplete-word-fwd\fR and \fIcomplete-word-back\fR editor commands

   400 (not bound to any keys by default) can be used to cycle up and down through

   401 the list of possible completions, replacing the current word with the next or

   402 previous word in the list.

   403 .PP

   404 The shell variable \fBfignore\fR can be set to a list of suffixes to be

   405 ignored by completion.  Consider the following:

   406 .IP "" 4

   407 > ls

   408 .br

   409 Makefile        condiments.h~   main.o          side.c

   410 .br

   411 README          main.c          meal            side.o

   412 .br

   413 condiments.h    main.c~

   414 .br

   415 > set fignore = (.o \\~)

   416 .br

   417 > emacs ma[^D]

   418 .br

   419 main.c   main.c~  main.o

   420 .br

   421 > emacs ma[tab]

   422 .br

   423 > emacs main.c

   424 .PP

   425 `main.c~' and `main.o' are ignored by completion (but not listing),

   426 because they end in suffixes in \fBfignore\fR.

   427 Note that a `\\' was needed in front of `~' to prevent it from being

   428 expanded to \fBhome\fR as described under \fBFilename substitution\fR.

   429 \fBfignore\fR is ignored if only one completion is possible.

   430 .PP

   431 If the \fBcomplete\fR shell variable is set to `enhance', completion

   432 1) ignores case and 2) considers periods, hyphens and underscores

   433 (`.', `\-' and `_') to be word separators and hyphens and underscores to

   434 be equivalent.  If you had the following files

   435 .IP "" 4

   436 comp.lang.c      comp.lang.perl   comp.std.c++

   437 .br

   438 comp.lang.c++    comp.std.c

   439 .PP

   440 and typed `mail \-f c.l.c[tab]', it would be completed to

   441 `mail \-f comp.lang.c', and ^D would list `comp.lang.c' and `comp.lang.c++'.

   442 `mail \-f c..c++[^D]' would list `comp.lang.c++' and `comp.std.c++'.  Typing

   443 `rm a\-\-file[^D]' in the following directory

   444 .IP "" 4

   445 A_silly_file    a-hyphenated-file    another_silly_file

   446 .PP

   447 would list all three files, because case is ignored and hyphens and

   448 underscores are equivalent.  Periods, however, are not equivalent to

   449 hyphens or underscores.

   450 .PP

   451 Completion and listing are affected by several other shell variables:

   452 \fBrecexact\fR can be set to complete on the shortest possible unique

   453 match, even if more typing might result in a longer match:

   454 .IP "" 4

   455 > ls

   456 .br

   457 fodder   foo      food     foonly

   458 .br

   459 > set recexact

   460 .br

   461 > rm fo[tab]

   462 .PP

   463 just beeps, because `fo' could expand to `fod' or `foo', but if we type

   464 another `o',

   465 .IP "" 4

   466 > rm foo[tab]

   467 .br

   468 > rm foo

   469 .PP

   470 the completion completes on `foo', even though `food' and `foonly'

   471 also match.

   472 \fBautoexpand\fR can be set to run the \fIexpand-history\fR editor command

   473 before each completion attempt, \fBautocorrect\fR can be set to

   474 spelling-correct the word to be completed (see \fBSpelling correction\fR)

   475 before each completion attempt and \fBcorrect\fR can be set to complete

   476 commands automatically after one hits `return'.

   477 \fBmatchbeep\fR can be set to make completion beep or not beep in a variety

   478 of situations, and \fBnobeep\fR can be set to never beep at all.

   479 \fBnostat\fR can be set to a list of directories and/or patterns that

   480 match directories to prevent the completion mechanism from \fIstat\fR(2)ing

   481 those directories.

   482 \fBlistmax\fR and \fBlistmaxrows\fR can be set to limit the number of items

   483 and rows (respectively) that are listed without asking first.

   484 \fBrecognize_only_executables\fR can be set to make the shell list only

   485 executables when listing commands, but it is quite slow.

   486 .PP

   487 Finally, the \fIcomplete\fR builtin command can be used to tell the shell how

   488 to complete words other than filenames, commands and variables.

   489 Completion and listing do not work on glob-patterns (see \fBFilename substitution\fR),

   490 but the \fIlist-glob\fR and \fIexpand-glob\fR editor commands perform

   491 equivalent functions for glob-patterns.

   492 .SS "Spelling correction (+)"

   493 The shell can sometimes correct the spelling of filenames, commands and variable names

   494 as well as completing and listing them.

   495 .PP

   496 Individual words can be spelling-corrected with the \fIspell-word\fR

   497 editor command (usually bound to M-s and M-S)

   498 and the entire input buffer with \fIspell-line\fR (usually bound to M-$).

   499 The \fBcorrect\fR shell variable can be set to `cmd' to correct the

   500 command name or `all' to correct the entire line each time return is typed,

   501 and \fBautocorrect\fR can be set to correct the word to be completed

   502 before each completion attempt.

   503 .PP

   504 When spelling correction is invoked in any of these ways and

   505 the shell thinks that any part of the command line is misspelled,

   506 it prompts with the corrected line:

   507 .IP "" 4

   508 > set correct = cmd

   509 .br

   510 > lz /usr/bin

   511 .br

   512 CORRECT>ls /usr/bin (y|n|e|a)?

   513 .PP

   514 One can answer `y' or space to execute the corrected line,

   515 `e' to leave the uncorrected command in the input buffer,

   516 `a' to abort the command as if `^C' had been hit, and

   517 anything else to execute the original line unchanged.

   518 .PP

   519 Spelling correction recognizes user-defined completions (see the

   520 \fIcomplete\fR builtin command).  If an input word in a position for

   521 which a completion is defined resembles a word in the completion list,

   522 spelling correction registers a misspelling and suggests the latter

   523 word as a correction.  However, if the input word does not match any of

   524 the possible completions for that position, spelling correction does

   525 not register a misspelling.

   526 .PP

   527 Like completion, spelling correction works anywhere in the line,

   528 pushing the rest of the line to the right and possibly leaving

   529 extra characters to the right of the cursor.

   530 .PP

   531 Beware: spelling correction is not guaranteed to work the way one intends,

   532 and is provided mostly as an experimental feature.

   533 Suggestions and improvements are welcome.

   534 .SS "Editor commands (+)"

   535 `bindkey' lists key bindings and `bindkey \-l' lists and briefly describes

   536 editor commands.

   537 Only new or especially interesting editor commands are described here.

   538 See \fIemacs\fR(1) and \fIvi\fR(1) for descriptions of each editor's

   539 key bindings.

   540 .PP

   541 The character or characters to which each command is bound by default is

   542 given in parentheses.  `^\fIcharacter\fR' means a control character and

   543 `M-\fIcharacter\fR' a meta character, typed as escape-\fIcharacter\fR

   544 on terminals without a meta key.  Case counts, but commands that are bound

   545 to letters by default are bound to both lower- and uppercase letters for

   546 convenience.

   547 .TP 8

   548 .B complete-word \fR(tab)

   549 Completes a word as described under \fBCompletion and listing\fR.

   550 .TP 8

   551 .B complete-word-back \fR(not bound)

   552 Like \fIcomplete-word-fwd\fR, but steps up from the end of the list.

   553 .TP 8

   554 .B complete-word-fwd \fR(not bound)

   555 Replaces the current word with the first word in the list of possible

   556 completions.  May be repeated to step down through the list.

   557 At the end of the list, beeps and reverts to the incomplete word.

   558 .TP 8

   559 .B complete-word-raw \fR(^X-tab)

   560 Like \fIcomplete-word\fR, but ignores user-defined completions.

   561 .TP 8

   562 .B copy-prev-word \fR(M-^_)

   563 Copies the previous word in the current line into the input buffer.

   564 See also \fIinsert-last-word\fR.

   565 .TP 8

   566 .B dabbrev-expand \fR(M-/)

   567 Expands the current word to the most recent preceding one for which

   568 the current is a leading substring, wrapping around the history list

   569 (once) if necessary.

   570 Repeating \fIdabbrev-expand\fR without any intervening typing

   571 changes to the next previous word etc., skipping identical matches

   572 much like \fIhistory-search-backward\fR does.

   573 .TP 8

   574 .B delete-char \fR(not bound)

   575 Deletes the character under the cursor.

   576 See also \fIdelete-char-or-list-or-eof\fR.

   577 .TP 8

   578 .B delete-char-or-eof \fR(not bound)

   579 Does \fIdelete-char\fR if there is a character under the cursor

   580 or \fIend-of-file\fR on an empty line.

   581 See also \fIdelete-char-or-list-or-eof\fR.

   582 .TP 8

   583 .B delete-char-or-list \fR(not bound)

   584 Does \fIdelete-char\fR if there is a character under the cursor

   585 or \fIlist-choices\fR at the end of the line.

   586 See also \fIdelete-char-or-list-or-eof\fR.

   587 .TP 8

   588 .B delete-char-or-list-or-eof \fR(^D)

   589 Does \fIdelete-char\fR if there is a character under the cursor,

   590 \fIlist-choices\fR at the end of the line

   591 or \fIend-of-file\fR on an empty line.

   592 See also those three commands, each of which does only a single action, and

   593 \fIdelete-char-or-eof\fR, \fIdelete-char-or-list\fR and \fIlist-or-eof\fR,

   594 each of which does a different two out of the three.

   595 .TP 8

   596 .B down-history \fR(down-arrow, ^N)

   597 Like \fIup-history\fR, but steps down, stopping at the original input line.

   598 .TP 8

   599 .B end-of-file \fR(not bound)

   600 Signals an end of file, causing the shell to exit unless the \fBignoreeof\fR

   601 shell variable (q.v.) is set to prevent this.

   602 See also \fIdelete-char-or-list-or-eof\fR.

   603 .TP 8

   604 .B expand-history \fR(M-space)

   605 Expands history substitutions in the current word.

   606 See \fBHistory substitution\fR.

   607 See also \fImagic-space\fR, \fItoggle-literal-history\fR and

   608 the \fBautoexpand\fR shell variable.

   609 .TP 8

   610 .B expand-glob \fR(^X-*)

   611 Expands the glob-pattern to the left of the cursor.

   612 See \fBFilename substitution\fR.

   613 .TP 8

   614 .B expand-line \fR(not bound)

   615 Like \fIexpand-history\fR, but

   616 expands history substitutions in each word in the input buffer,

   617 .TP 8

   618 .B expand-variables \fR(^X-$)

   619 Expands the variable to the left of the cursor.

   620 See \fBVariable substitution\fR.

   621 .TP 8

   622 .B history-search-backward \fR(M-p, M-P)

   623 Searches backwards through the history list for a command beginning with

   624 the current contents of the input buffer up to the cursor and copies it

   625 into the input buffer.

   626 The search string may be a glob-pattern (see \fBFilename substitution\fR)

   627 containing `*', `?', `[]' or `{}'.

   628 \fIup-history\fR and \fIdown-history\fR will proceed from the

   629 appropriate point in the history list.

   630 Emacs mode only.

   631 See also \fIhistory-search-forward\fR and \fIi-search-back\fR.

   632 .TP 8

   633 .B history-search-forward \fR(M-n, M-N)

   634 Like \fIhistory-search-backward\fR, but searches forward.

   635 .TP 8

   636 .B i-search-back \fR(not bound)

   637 Searches backward like \fIhistory-search-backward\fR, copies the first match

   638 into the input buffer with the cursor positioned at the end of the pattern,

   639 and prompts with `bck: ' and the first match.  Additional characters may be

   640 typed to extend the search, \fIi-search-back\fR may be typed to continue

   641 searching with the same pattern, wrapping around the history list if

   642 necessary, (\fIi-search-back\fR must be bound to a

   643 single character for this to work) or one of the following special characters

   644 may be typed:

   645 .PP

   646 .RS +8

   647 .RS +4

   648 .PD 0

   649 .TP 8

   650 ^W

   651 Appends the rest of the word under the cursor to the search pattern.

   652 .TP 8

   653 delete (or any character bound to \fIbackward-delete-char\fR)

   654 Undoes the effect of the last character typed and deletes a character

   655 from the search pattern if appropriate.

   656 .TP 8

   657 ^G

   658 If the previous search was successful, aborts the entire search.

   659 If not, goes back to the last successful search.

   660 .TP 8

   661 escape

   662 Ends the search, leaving the current line in the input buffer.

   663 .RE

   664 .PD

   665 .PP

   666 Any other character not bound to \fIself-insert-command\fR terminates the

   667 search, leaving the current line in the input buffer, and

   668 is then interpreted as normal input.  In particular, a carriage return

   669 causes the current line to be executed.

   670 Emacs mode only.

   671 See also \fIi-search-fwd\fR and \fIhistory-search-backward\fR.

   672 .RE

   673 .TP 8

   674 .B i-search-fwd \fR(not bound)

   675 Like \fIi-search-back\fR, but searches forward.

   676 .TP 8

   677 .B insert-last-word \fR(M-_)

   678 Inserts the last word of the previous input line (`!$') into the input buffer.

   679 See also \fIcopy-prev-word\fR.

   680 .TP 8

   681 .B list-choices \fR(M-^D)

   682 Lists completion possibilities as described under \fBCompletion and listing\fR.

   683 See also \fIdelete-char-or-list-or-eof\fR and \fIlist-choices-raw\fR.

   684 .TP 8

   685 .B list-choices-raw \fR(^X-^D)

   686 Like \fIlist-choices\fR, but ignores user-defined completions.

   687 .TP 8

   688 .B list-glob \fR(^X-g, ^X-G)

   689 Lists (via the \fIls\-F\fR builtin) matches to the glob-pattern

   690 (see \fBFilename substitution\fR) to the left of the cursor.

   691 .TP 8

   692 .B list-or-eof \fR(not bound)

   693 Does \fIlist-choices\fR

   694 or \fIend-of-file\fR on an empty line.

   695 See also \fIdelete-char-or-list-or-eof\fR.

   696 .TP 8

   697 .B magic-space \fR(not bound)

   698 Expands history substitutions in the current line,

   699 like \fIexpand-history\fR, and inserts a space.

   700 \fImagic-space\fR is designed to be bound to the space bar,

   701 but is not bound by default.

   702 .TP 8

   703 .B normalize-command \fR(^X-?)

   704 Searches for the current word in PATH and, if it is found, replaces it with

   705 the full path to the executable.  Special characters are quoted.  Aliases are

   706 expanded and quoted but commands within aliases are not.  This command is

   707 useful with commands that take commands as arguments, e.g., `dbx' and `sh \-x'.

   708 .TP 8

   709 .B normalize-path \fR(^X-n, ^X-N)

   710 Expands the current word as described under the `expand' setting

   711 of the \fBsymlinks\fR shell variable.

   712 .TP 8

   713 .B overwrite-mode \fR(unbound)

   714 Toggles between input and overwrite modes.

   715 .TP 8

   716 .B run-fg-editor \fR(M-^Z)

   717 Saves the current input line and

   718 looks for a stopped job with a name equal to the last component of the

   719 file name part of the \fBEDITOR\fR or \fBVISUAL\fR environment variables,

   720 or, if neither is set, `ed' or `vi'.

   721 If such a job is found, it is restarted as if `fg %\fIjob\fR' had been

   722 typed.  This is used to toggle back and forth between an editor and

   723 the shell easily.  Some people bind this command to `^Z' so they

   724 can do this even more easily.

   725 .TP

   726 .B run-help \fR(M-h, M-H)

   727 Searches for documentation on the current command, using the same notion of

   728 `current command' as the completion routines, and prints it.  There is no way

   729 to use a pager; \fIrun-help\fR is designed for short help files.

   730 If the special alias \fBhelpcommand\fR is defined, it is run with the

   731 command name as a sole argument.  Else,

   732 documentation should be in a file named \fIcommand\fR.help, \fIcommand\fR.1,

   733 \fIcommand\fR.6, \fIcommand\fR.8 or \fIcommand\fR, which should be in one

   734 of the directories listed in the \fBHPATH\fR environment variable.

   735 If there is more than one help file only the first is printed.

   736 .TP 8

   737 .B self-insert-command \fR(text characters)

   738 In insert mode (the default), inserts the typed character into the input line after the character under the cursor.

   739 In overwrite mode, replaces the character under the cursor with the typed character.

   740 The input mode is normally preserved between lines, but the

   741 \fBinputmode\fR shell variable can be set to `insert' or `overwrite' to put the

   742 editor in that mode at the beginning of each line.

   743 See also \fIoverwrite-mode\fR.

   744 .TP 8

   745 .B sequence-lead-in \fR(arrow prefix, meta prefix, ^X)

   746 Indicates that the following characters are part of a

   747 multi-key sequence.  Binding a command to a multi-key sequence really creates

   748 two bindings: the first character to \fIsequence-lead-in\fR and the

   749 whole sequence to the command.  All sequences beginning with a character

   750 bound to \fIsequence-lead-in\fR are effectively bound to \fIundefined-key\fR

   751 unless bound to another command.

   752 .TP 8

   753 .B spell-line \fR(M-$)

   754 Attempts to correct the spelling of each word in the input buffer, like

   755 \fIspell-word\fR, but ignores words whose first character is one of

   756 `\-', `!', `^' or `%', or which contain `\\', `*' or `?', to avoid problems

   757 with switches, substitutions and the like.

   758 See \fBSpelling correction\fR.

   759 .TP 8

   760 .B spell-word \fR(M-s, M-S)

   761 Attempts to correct the spelling of the current word as described

   762 under \fBSpelling correction\fR.

   763 Checks each component of a word which appears to be a pathname.

   764 .TP 8

   765 .B toggle-literal-history \fR(M-r, M-R)

   766 Expands or `unexpands' history substitutions in the input buffer.

   767 See also \fIexpand-history\fR and the \fBautoexpand\fR shell variable.

   768 .TP 8

   769 .B undefined-key \fR(any unbound key)

   770 Beeps.

   771 .TP 8

   772 .B up-history \fR(up-arrow, ^P)

   773 Copies the previous entry in the history list into the input buffer.

   774 If \fBhistlit\fR is set, uses the literal form of the entry.

   775 May be repeated to step up through the history list, stopping at the top.

   776 .TP 8

   777 .B vi-search-back \fR(?)

   778 Prompts with `?' for a search string (which may be a glob-pattern, as with

   779 \fIhistory-search-backward\fR), searches for it and copies it into the

   780 input buffer.  The bell rings if no match is found.

   781 Hitting return ends the search and leaves the last match in the input

   782 buffer.

   783 Hitting escape ends the search and executes the match.

   784 \fIvi\fR mode only.

   785 .TP 8

   786 .B vi-search-fwd \fR(/)

   787 Like \fIvi-search-back\fR, but searches forward.

   788 .TP 8

   789 .B which-command \fR(M-?)

   790 Does a \fIwhich\fR (see the description of the builtin command) on the

   791 first word of the input buffer.

   792 .TP 8

   793 .B yank-pop \fR(M-y)

   794 When executed immediately after a \fIyank\fR or another \fIyank-pop\fR,

   795 replaces the yanked string with the next previous string from the

   796 killring. This also has the effect of rotating the killring, such that

   797 this string will be considered the most recently killed by a later

   798 \fIyank\fR command. Repeating \fIyank-pop\fR will cycle through the

   799 killring any number of times.

   800 .SS "Lexical structure"

   801 The shell splits input lines into words at blanks and tabs.  The special

   802 characters `&', `|', `;', `<', `>', `(', and `)' and the doubled characters

   803 `&&', `||', `<<' and `>>' are always separate words, whether or not they are

   804 surrounded by whitespace.

   805 .PP

   806 When the shell's input is not a terminal, the character `#' is taken to begin a

   807 comment.  Each `#' and the rest of the input line on which it appears is

   808 discarded before further parsing.

   809 .PP

   810 A special character (including a blank or tab) may be prevented from having

   811 its special meaning, and possibly made part of another word, by preceding it

   812 with a backslash (`\\') or enclosing it in single (`''), double (`"') or

   813 backward (``') quotes.  When not otherwise quoted a newline preceded by a `\\'

   814 is equivalent to a blank, but inside quotes this sequence results in a

   815 newline.

   816 .PP

   817 Furthermore, all \fBSubstitutions\fR (see below) except \fBHistory substitution\fR

   818 can be prevented by enclosing the strings (or parts of strings)

   819 in which they appear with single quotes or by quoting the crucial character(s)

   820 (e.g., `$' or ``' for \fBVariable substitution\fR or \fBCommand substitution\fR respectively)

   821 with `\\'.  (\fBAlias substitution\fR is no exception: quoting in any way any

   822 character of a word for which an \fIalias\fR has been defined prevents

   823 substitution of the alias.  The usual way of quoting an alias is to precede it

   824 with a backslash.) \fBHistory substitution\fR is prevented by

   825 backslashes but not by single quotes.  Strings quoted with double or backward

   826 quotes undergo \fBVariable substitution\fR and \fBCommand substitution\fR, but other

   827 substitutions are prevented.

   828 .PP

   829 Text inside single or double quotes becomes a single word (or part of one).

   830 Metacharacters in these strings, including blanks and tabs, do not form

   831 separate words.  Only in one special case (see \fBCommand substitution\fR

   832 below) can a double-quoted string yield parts of more than one word;

   833 single-quoted strings never do.  Backward quotes are special: they signal

   834 \fBCommand substitution\fR (q.v.), which may result in more than one word.

   835 .PP

   836 Quoting complex strings, particularly strings which themselves contain quoting

   837 characters, can be confusing.  Remember that quotes need not be used as they are

   838 in human writing!  It may be easier to quote not an entire string, but only

   839 those parts of the string which need quoting, using different types of quoting

   840 to do so if appropriate.

   841 .PP

   842 The \fBbackslash_quote\fR shell variable (q.v.) can be set to make backslashes

   843 always quote `\\', `'', and `"'.  (+) This may make complex quoting tasks

   844 easier, but it can cause syntax errors in \fIcsh\fR(1) scripts.

   845 .SS Substitutions

   846 We now describe the various transformations the shell performs on the input in

   847 the order in which they occur.  We note in passing the data structures involved

   848 and the commands and variables which affect them.  Remember that substitutions

   849 can be prevented by quoting as described under \fBLexical structure\fR.

   850 .SS "History substitution"

   851 Each command, or ``event'', input from the terminal is saved in the history

   852 list.  The previous command is always saved, and the \fBhistory\fR shell

   853 variable can be set to a number to save that many commands.  The \fBhistdup\fR

   854 shell variable can be set to not save duplicate events or consecutive duplicate

   855 events.

   856 .PP

   857 Saved commands are numbered sequentially from 1 and stamped with the time.

   858 It is not usually necessary to use event numbers, but the current event number

   859 can be made part of the prompt by placing an `!' in the \fBprompt\fR shell variable.

   860 .PP

   861 The shell actually saves history in expanded and literal (unexpanded) forms.

   862 If the \fBhistlit\fR shell variable is set, commands that display and store

   863 history use the literal form.

   864 .PP

   865 The \fIhistory\fR builtin command can print, store in a file, restore

   866 and clear the history list at any time,

   867 and the \fBsavehist\fR and \fBhistfile\fR shell variables can be can be set to

   868 store the history list automatically on logout and restore it on login.

   869 .PP

   870 History substitutions introduce words from the history list into the input

   871 stream, making it easy to repeat commands, repeat arguments of a previous

   872 command in the current command, or fix spelling mistakes in the previous

   873 command with little typing and a high degree of confidence.

   874 .PP

   875 History substitutions begin with the character `!'.  They may begin anywhere in

   876 the input stream, but they do not nest.  The `!' may be preceded by a `\\' to

   877 prevent its special meaning; for convenience, a `!' is passed unchanged when it

   878 is followed by a blank, tab, newline, `=' or `('.  History substitutions also

   879 occur when an input line begins with `^'.  This special abbreviation will be

   880 described later.  The characters used to signal history substitution (`!' and

   881 `^') can be changed by setting the \fBhistchars\fR shell variable.  Any input

   882 line which contains a history substitution is printed before it is executed.

   883 .PP

   884 A history substitution may have an ``event specification'', which indicates

   885 the event from which words are to be taken, a ``word designator'',

   886 which selects particular words from the chosen event, and/or a ``modifier'',

   887 which manipulates the selected words.

   888 .PP

   889 An event specification can be

   890 .PP

   891 .PD 0

   892 .RS +4

   893 .TP 8

   894 .I n

   895 A number, referring to a particular event

   896 .TP 8

   897 \-\fIn\fR

   898 An offset, referring to the event \fIn\fR before the current event

   899 .TP 8

   900 #

   901 The current event.

   902 This should be used carefully in \fIcsh\fR(1), where there is no check for

   903 recursion.  \fItcsh\fR allows 10 levels of recursion.  (+)

   904 .TP 8

   905 !

   906 The previous event (equivalent to `\-1')

   907 .TP 8

   908 .I s

   909 The most recent event whose first word begins with the string \fIs\fR

   910 .TP 8

   911 ?\fIs\fR?

   912 The most recent event which contains the string \fIs\fR.

   913 The second `?' can be omitted if it is immediately followed by a newline.

   914 .RE

   915 .PD

   916 .PP

   917 For example, consider this bit of someone's history list:

   918 .IP "" 4

   919 \ 9  8:30    nroff \-man wumpus.man

   920 .br

   921 10  8:31    cp wumpus.man wumpus.man.old

   922 .br

   923 11  8:36    vi wumpus.man

   924 .br

   925 12  8:37    diff wumpus.man.old wumpus.man

   926 .PP

   927 The commands are shown with their event numbers and time stamps.

   928 The current event, which we haven't typed in yet, is event 13.

   929 `!11' and `!\-2' refer to event 11.

   930 `!!' refers to the previous event, 12.  `!!' can be abbreviated `!' if it is

   931 followed by `:' (`:' is described below).

   932 `!n' refers to event 9, which begins with `n'.

   933 `!?old?' also refers to event 12, which contains `old'.

   934 Without word designators or modifiers history references simply expand to the

   935 entire event, so we might type `!cp' to redo the copy command or `!!|more'

   936 if the `diff' output scrolled off the top of the screen.

   937 .PP

   938 History references may be insulated from the surrounding text with braces if

   939 necessary.  For example, `!vdoc' would look for a command beginning with

   940 `vdoc', and, in this example, not find one, but `!{v}doc' would expand

   941 unambiguously to `vi wumpus.mandoc'.

   942 Even in braces, history substitutions do not nest.

   943 .PP

   944 (+) While \fIcsh\fR(1) expands, for example, `!3d' to event 3 with the

   945 letter `d' appended to it, \fItcsh\fR expands it to the last event beginning

   946 with `3d'; only completely numeric arguments are treated as event numbers.

   947 This makes it possible to recall events beginning with numbers.

   948 To expand `!3d' as in \fIcsh\fR(1) say `!{3}d'.

   949 .PP

   950 To select words from an event we can follow the event specification by a `:'

   951 and a designator for the desired words.  The words of an input line are

   952 numbered from 0, the first (usually command) word being 0, the second word

   953 (first argument) being 1, etc.  The basic word designators are:

   954 .PP

   955 .PD 0

   956 .RS +4

   957 .TP 8

   958 0

   959 The first (command) word

   960 .TP 8

   961 .I n

   962 The \fIn\fRth argument

   963 .TP 8

   964 ^

   965 The first argument, equivalent to `1'

   966 .TP 8

   967 $

   968 The last argument

   969 .TP 8

   970 %

   971 The word matched by an ?\fIs\fR? search

   972 .TP 8

   973 .I x\-y

   974 A range of words

   975 .TP 8

   976 .I \-y

   977 Equivalent to \fI`0\-y'\fR

   978 .TP 8

   979 *

   980 Equivalent to `^\-$', but returns nothing if the event contains only 1 word

   981 .TP 8

   982 .I x*

   983 Equivalent to \fI`x\-$'\fR

   984 .TP 8

   985 .I x\-

   986 Equivalent to \fI`x*'\fR, but omitting the last word (`$')

   987 .PD

   988 .RE

   989 .PP

   990 Selected words are inserted into the command line separated by single blanks.

   991 For example, the `diff' command in the previous example might have been

   992 typed as `diff !!:1.old !!:1' (using `:1' to select the first argument

   993 from the previous event) or `diff !\-2:2 !\-2:1' to select and swap the

   994 arguments from the `cp' command.  If we didn't care about the order of the

   995 `diff' we might have said `diff !\-2:1\-2' or simply `diff !\-2:*'.

   996 The `cp' command might have been written `cp wumpus.man !#:1.old', using `#'

   997 to refer to the current event.

   998 `!n:\- hurkle.man' would reuse the first two words from the `nroff' command

   999 to say `nroff \-man hurkle.man'.

  1000 .PP

  1001 The `:' separating the event specification from the word designator can be

  1002 omitted if the argument selector begins with a `^', `$', `*', `%' or `\-'.

  1003 For example, our `diff' command might have been `diff !!^.old !!^' or,

  1004 equivalently, `diff !!$.old !!$'.  However, if `!!' is abbreviated `!',

  1005 an argument selector beginning with `\-' will be interpreted as an event

  1006 specification.

  1007 .PP

  1008 A history reference may have a word designator but no event specification.

  1009 It then references the previous command.

  1010 Continuing our `diff' example, we could have said simply `diff

  1011 !^.old !^' or, to get the arguments in the opposite order, just `diff !*'.

  1012 .PP

  1013 The word or words in a history reference can be edited, or ``modified'',

  1014 by following it with one or more modifiers, each preceded by a `:':

  1015 .PP

  1016 .PD 0

  1017 .RS +4

  1018 .TP 8

  1019 h

  1020 Remove a trailing pathname component, leaving the head.

  1021 .TP 8

  1022 t

  1023 Remove all leading pathname components, leaving the tail.

  1024 .TP 8

  1025 r

  1026 Remove a filename extension `.xxx', leaving the root name.

  1027 .TP 8

  1028 e

  1029 Remove all but the extension.

  1030 .TP 8

  1031 u

  1032 Uppercase the first lowercase letter.

  1033 .TP 8

  1034 l

  1035 Lowercase the first uppercase letter.

  1036 .TP 8

  1037 s\fI/l/r/\fR

  1038 Substitute \fIl\fR for \fIr\fR.

  1039 \fIl\fR is simply a string like \fIr\fR, not a regular expression as in

  1040 the eponymous \fIed\fR(1) command.

  1041 Any character may be used as the delimiter in place of `/';

  1042 a `\\' can be used to quote the delimiter inside \fIl\fR and \fIr\fR.

  1043 The character `&' in the \fIr\fR is replaced by \fIl\fR; `\\' also quotes `&'.

  1044 If \fIl\fR is empty (``''), the \fIl\fR from a previous substitution or the

  1045 \fIs\fR from a previous search or event number in event specification is used.

  1046 The trailing delimiter may be omitted if it is immediately followed by a newline.

  1047 .TP 8

  1048 &

  1049 Repeat the previous substitution.

  1050 .TP 8

  1051 g

  1052 Apply the following modifier once to each word.

  1053 .TP 8

  1054 a (+)

  1055 Apply the following modifier as many times as possible to a single word.

  1056 `a' and `g' can be used together to apply a modifier globally.

  1057 With the `s' modifier, only the patterns contained in the original word are

  1058 substituted, not patterns that contain any substitution result.

  1059 .TP 8

  1060 p

  1061 Print the new command line but do not execute it.

  1062 .TP 8

  1063 q

  1064 Quote the substituted words, preventing further substitutions.

  1065 .TP 8

  1066 x

  1067 Like q, but break into words at blanks, tabs and newlines.

  1068 .PD

  1069 .RE

  1070 .PP

  1071 Modifiers are applied to only the first modifiable word (unless `g' is used).

  1072 It is an error for no word to be modifiable.

  1073 .PP

  1074 For example, the `diff' command might have been written as `diff wumpus.man.old

  1075 !#^:r', using `:r' to remove `.old' from the first argument on the same line

  1076 (`!#^').  We could say `echo hello out there', then `echo !*:u' to capitalize

  1077 `hello', `echo !*:au' to say it out loud, or `echo !*:agu' to really shout.

  1078 We might follow `mail \-s "I forgot my password" rot' with `!:s/rot/root' to

  1079 correct the spelling of `root' (but see \fBSpelling correction\fR for a

  1080 different approach).

  1081 .PP

  1082 There is a special abbreviation for substitutions.

  1083 `^', when it is the first character on an input line, is equivalent to `!:s^'.

  1084 Thus we might have said `^rot^root' to make the spelling correction in the

  1085 previous example.

  1086 This is the only history substitution which does not explicitly begin with `!'.

  1087 .PP

  1088 (+) In \fIcsh\fR as such, only one modifier may be applied to each history

  1089 or variable expansion.  In \fItcsh\fR, more than one may be used, for example

  1090 .IP "" 4

  1091 % mv wumpus.man /usr/man/man1/wumpus.1

  1092 .br

  1093 % man !$:t:r

  1094 .br

  1095 man wumpus

  1096 .PP

  1097 In \fIcsh\fR, the result would be `wumpus.1:r'.  A substitution followed by a

  1098 colon may need to be insulated from it with braces:

  1099 .IP "" 4

  1100 > mv a.out /usr/games/wumpus

  1101 .br

  1102 > setenv PATH !$:h:$PATH

  1103 .br

  1104 Bad ! modifier: $.

  1105 .br

  1106 > setenv PATH !{\-2$:h}:$PATH

  1107 .br

  1108 setenv PATH /usr/games:/bin:/usr/bin:.

  1109 .PP

  1110 The first attempt would succeed in \fIcsh\fR but fails in \fItcsh\fR,

  1111 because \fItcsh\fR expects another modifier after the second colon

  1112 rather than `$'.

  1113 .PP

  1114 Finally, history can be accessed through the editor as well as through

  1115 the substitutions just described.

  1116 The \fIup-\fR and \fIdown-history\fR, \fIhistory-search-backward\fR and

  1117 \fI-forward\fR, \fIi-search-back\fR and \fI-fwd\fR,

  1118 \fIvi-search-back\fR and \fI-fwd\fR, \fIcopy-prev-word\fR

  1119 and \fIinsert-last-word\fR editor commands search for

  1120 events in the history list and copy them into the input buffer.

  1121 The \fItoggle-literal-history\fR editor command switches between the

  1122 expanded and literal forms of history lines in the input buffer.

  1123 \fIexpand-history\fR and \fIexpand-line\fR expand history substitutions

  1124 in the current word and in the entire input buffer respectively.

  1125 .SS "Alias substitution"

  1126 The shell maintains a list of aliases which can be set, unset and printed by

  1127 the \fIalias\fR and \fIunalias\fR commands.  After a command line is parsed

  1128 into simple commands (see \fBCommands\fR) the first word of each command,

  1129 left-to-right, is checked to see if it has an alias.  If so, the first word is

  1130 replaced by the alias.  If the alias contains a history reference, it undergoes

  1131 \fBHistory substitution\fR (q.v.) as though the original command were the

  1132 previous input line.  If the alias does not contain a history reference, the

  1133 argument list is left untouched.

  1134 .PP

  1135 Thus if the alias for `ls' were `ls \-l' the command `ls /usr' would become `ls