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BUILTIN(1)             DragonFly General Commands Manual            BUILTIN(1)

NAME

builtin, !, %, ., :, @, [, {, }, alias, alloc, bg, bind, bindkey, break, breaksw, builtins, case, cd, chdir, command, complete, continue, default, dirs, do, done, echo, echotc, elif, else, end, endif, endsw, esac, eval, exec, exit, export, false, fc, fg, filetest, fi, for, foreach, getopts, glob, goto, hash, hashstat, history, hup, if, jobid, jobs, kill, let, limit, local, log, login, logout, ls-F, nice, nohup, notify, onintr, popd, printenv, printf, pushd, pwd, read, readonly, rehash, repeat, return, sched, set, setenv, settc, setty, setvar, shift, source, stop, suspend, switch, telltc, termname, test, then, time, times, trap, true, type, ulimit, umask, unalias, uncomplete, unhash, unlimit, unset, unsetenv, until, wait, where, which, while, wordexp -- shell built-in commands

SYNOPSIS

See the built-in command description in the appropriate shell manual page.

DESCRIPTION

Shell builtin commands are commands that can be executed within the run- ning shell's process. Note that, in the case of csh(1) builtin commands, the command is executed in a subshell if it occurs as any component of a pipeline except the last. If a command specified to the shell contains a slash `/', the shell will not execute a builtin command, even if the last component of the speci- fied command matches the name of a builtin command. Thus, while specify- ing ``echo'' causes a builtin command to be executed under shells that support the echo builtin command, specifying ``/bin/echo'' or ``./echo'' does not. While some builtin commands may exist in more than one shell, their oper- ation may be different under each shell which supports them. Below is a table which lists shell builtin commands, the standard shells that sup- port them and whether they exist as standalone utilities. Only builtin commands for the csh(1) and sh(1) shells are listed here. Consult a shell's manual page for details on the operation its builtin commands. Beware that the sh(1) manual page, at least, calls some of these commands ``built-in commands'' and some of them ``reserved words''. Users of other shells may need to consult an info(1) page or other sources of documentation. Commands marked ``No**'' under External do exist externally, but are implemented as scripts using a builtin command of the same name. Command External csh(1) sh(1) ! No No Yes % No Yes No . No No Yes : No Yes Yes @ No Yes No [ Yes No Yes { No No Yes } No No Yes alias No** Yes Yes alloc No Yes No bg No** Yes Yes bind No No Yes bindkey No Yes No break No Yes Yes breaksw No Yes No builtin No No Yes builtins No Yes No case No Yes Yes cd No** Yes Yes chdir No Yes Yes command No** No Yes complete No Yes No continue No Yes Yes default No Yes No dirs No Yes No do No No Yes done No No Yes echo Yes Yes Yes echotc No Yes No elif No No Yes else No Yes Yes end No Yes No endif No Yes No endsw No Yes No esac No No Yes eval No Yes Yes exec No Yes Yes exit No Yes Yes export No No Yes false Yes No Yes fc No** No Yes fg No** Yes Yes filetest No Yes No fi No No Yes for No No Yes foreach No Yes No getopts No** No Yes glob No Yes No goto No Yes No hash No No Yes hashstat No Yes No history No Yes No hup No Yes No if No Yes Yes jobid No No Yes jobs No** Yes Yes kill Yes Yes Yes let No No Yes limit No Yes No local No No Yes log No Yes No login Yes Yes No logout No Yes No ls-F No Yes No nice Yes Yes No nohup Yes Yes No notify No Yes No onintr No Yes No popd No Yes No printenv Yes Yes No printf Yes No Yes pushd No Yes No pwd Yes No Yes read No** No Yes readonly No No Yes rehash No Yes No repeat No Yes No return No No Yes sched No Yes No set No Yes Yes setenv No Yes No settc No Yes No setty No Yes No setvar No No Yes shift No Yes Yes source No Yes No stop No Yes No suspend No Yes No switch No Yes No telltc No Yes No termname No Yes No test Yes No Yes then No No Yes time Yes Yes No times No No Yes trap No No Yes true Yes No Yes type No No Yes ulimit No No Yes umask No** Yes Yes unalias No** Yes Yes uncomplete No Yes No unhash No Yes No unlimit No Yes No unset No Yes Yes unsetenv No Yes No until No No Yes wait No** Yes Yes where No Yes No which Yes Yes No while No Yes Yes wordexp No No Yes

SEE ALSO

csh(1), echo(1), false(1), info(1), kill(1), login(1), nice(1), nohup(1), printenv(1), printf(1), pwd(1), sh(1), test(1), time(1), true(1), which(1)

HISTORY

The builtin manual page first appeared in FreeBSD 3.4.

AUTHORS

This manual page was written by Sheldon Hearn <sheldonh@FreeBSD.org>. DragonFly 3.5 May 18, 2012 DragonFly 3.5 unset(n) Tcl Built-In Commands unset(n) ______________________________________________________________________________

NAME

unset - Delete variables

SYNOPSIS

unset ?-nocomplain? ?--? ?name name name ...? ______________________________________________________________________________

DESCRIPTION

This command removes one or more variables. Each name is a variable name, specified in any of the ways acceptable to the set command. If a name refers to an element of an array then that element is removed without affecting the rest of the array. If a name consists of an array name with no parenthesized index, then the entire array is deleted. The unset command returns an empty string as result. If -nocomplain is specified as the first argument, any possible errors are suppressed. The option may not be abbreviated, in order to disambiguate it from possible variable names. The option -- indicates the end of the options, and should be used if you wish to remove a variable with the same name as any of the options. If an error occurs during variable deletion, any variables after the named one causing the error are not deleted. An error can occur when the named variable does not exist, or the name refers to an array element but the variable is a scalar, or the name refers to a variable in a non-existent namespace.

EXAMPLE

Create an array containing a mapping from some numbers to their squares and remove the array elements for non-prime numbers: array set squares { 1 1 6 36 2 4 7 49 3 9 8 64 4 16 9 81 5 25 10 100 } puts "The squares are:" parray squares unset squares(1) squares(4) squares(6) unset squares(8) squares(9) squares(10) puts "The prime squares are:" parray squares

SEE ALSO

set(n), trace(n), upvar(n)

KEYWORDS

remove, variable Tcl 8.4 unset(n)

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