DragonFly On-Line Manual Pages
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, wordexp2 - 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
running 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
specified command matches the name of a builtin command. Thus, while
specifying "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
operation may be different under each shell which supports them. Below
is a table which lists shell builtin commands, the standard shells that
support 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
wordexp2 No No Yes
Note that the wordexp and wordexp2 commands are only meant to be used by
wordexp(3) and not by the user.
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), wordexp(3)
HISTORY
The builtin manual page first appeared in FreeBSD 3.4.
AUTHORS
This manual page was written by Sheldon Hearn <sheldonh@FreeBSD.org>.
DragonFly 5.9-DEVELOPMENT October 9, 2020 DragonFly 5.9-DEVELOPMENT
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)