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select(1)

Name | Description | See Also

Name

shell_builtins, case, for, foreach, function, if, repeat, select, switch, until, while– shell command interpreter built-in commands

Description

The shell command interpreters csh(1), ksh(1), ksh93(1), and sh(1) have special built-in commands. The commands case, for, foreach, function, if, repeat, select, switch, until, and while are commands in the syntax recognized by the shells. They are described in the Commands section of the manual pages of the respective shells. In ksh93(1), fc, hash, stop, suspend, times, and type are aliases by default. In ksh93, the following built-ins are bound to the /bin pathname by default and are invoked if the pathname search encounters an executable command of that name in the /bin or /usr/bin directory: cat, chown, getconf, head, mkdir, rmdir, tee, uniq, and wc.

The remaining commands listed in the following table are built into the shells for reasons such as efficiency or data sharing between command invocations. They are described on their respective manual pages.

Command	Shell
++**alias	csh, ksh, ksh93
bg	csh, ksh, ksh93, sh
+*break	csh, ksh, ksh93, sh
builtin	ksh93
case	csh, ksh, ksh93, sh
cat	ksh93
cd	csh, ksh, ksh93, sh
chdir	csh, sh
chown	ksh93
command	ksh93
+*continue	csh, ksh, ksh93, sh
dirs	csh
disown	ksh93
echo	csh, ksh, ksh93, sh
+*eval	csh, ksh, ksh93, sh
+*exec	csh, ksh, ksh93, sh
+*exit	csh, ksh, ksh93, sh
++**export	ksh, ksh93, sh
false	ksh, ksh93
fc	ksh, ksh93
fg	csh, ksh, ksh93, sh
for	ksh, ksh93, sh
foreach	csh
function	ksh, ksh93
getconf	ksh93
getopts	ksh, ksh93, sh
glob	csh
goto	csh
hash	ksh, ksh93, sh
hashstat	csh
head	ksh93
hist	ksh93
history	csh
if	csh, ksh, ksh93, sh
jobs	csh, ksh, ksh93, sh
kill	csh, ksh, ksh93, sh
let	ksh, ksh93,
limit	csh
login	csh, ksh, ksh93, sh
logout	csh
mkdir	ksh93
nice	csh
+*newgrp	ksh, ksh93, sh
nohup	csh
notify	csh
onintr	csh
popd	csh
print	ksh, ksh93
printf	ksh93
pushd	csh
pwd	ksh, ksh93, sh
read	ksh, ksh93, sh
++**readonly	ksh, ksh93, sh
rehash	csh
repeat	csh
+*return	ksh, ksh93, sh
select	ksh, ksh93
+set	csh, ksh, ksh93, sh
setenv	csh
shift	csh, ksh, ksh93, sh
sleep	ksh93
source	csh
stop	csh, ksh, ksh93, sh
suspend	csh, ksh, sh
switch	csh
tee	ksh93
test	ksh, ksh93, sh
time	csh
*times	ksh, ksh93, sh
*+trap	ksh, ksh93, sh
true	ksh, ksh93
type	ksh, ksh93, sh
++**typeset	ksh, ksh93
ulimit	ksh, ksh93, sh
umask	csh, ksh, ksh93, sh
+unalias	csh, ksh, ksh93
unhash	csh
uniq	ksh93
unlimit	csh
+unset	csh, ksh, ksh93, sh
unsetenv	csh
until	ksh, ksh93, sh
*wait	csh, ksh, ksh93, sh
whence	ksh, ksh93
while	csh, ksh, ksh93, sh

Bourne Shell, sh, Special Commands

Input/output redirection is now permitted for these commands. File descriptor 1 is the default output location. When Job Control is enabled, additional Special Commands are added to the shell's environment.

In addition to these built-in reserved command words, sh also uses:

:

No effect; the command does nothing. A zero exit code is returned.

.filename

Read and execute commands from filename and return. The search path specified by PATH is used to find the directory containing filename.

C shell, csh

Built-in commands are executed within the C shell. If a built-in command occurs as any component of a pipeline except the last, it is executed in a subshell. In addition to these built-in reserved command words, csh also uses:

:

Null command. This command is interpreted, but performs no action.

Korn Shell, ksh, Special Commands

Input/Output redirection is permitted. Unless otherwise indicated, the output is written on file descriptor 1 and the exit status, when there is no syntax error, is zero.

Commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

1. Variable assignment lists preceding the command remain in effect when the command completes.

2. I/O redirections are processed after variable assignments.

3. Errors cause a script that contains them to abort.

4. Words, following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a variable assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation are not performed.

In addition to these built-in reserved command words, ksh also uses:

* : [ arg . . . ]

The command only expands parameters.

* .file [ arg . . . ]

Read the complete file then execute the commands. The commands are executed in the current shell environment. The search path specified by PATH is used to find the directory containing file. If any arguments arg are specified, they become the positional parameters. Otherwise, the positional parameters are unchanged. The exit status is the exit status of the last command executed. the loop termination test.

Korn Shell, ksh93, Special Commands

Input/Output redirection is permitted. Unless otherwise indicated, the output is written on file descriptor 1 and the exit status, when there is no syntax error, is zero.

Except for :, true, false, echo, newgrp, and login, all built-in commands accept -- to indicate end of options. They also interpret the option --man as a request to display the manual page onto standard error and -? as a help request which prints a usage message on standard error.

Commands that are preceded by one or two + are treated specially in the following ways:

1. Variable assignment lists preceding the command remain in effect when the command completes.

2. I/O redirections are processed after variable assignments.

3. Errors cause a script that contains them to abort.

4. They are not valid function names.

5. Words, following a command preceded by ++ that are in the format of a variable assignment, are expanded with the same rules as a variable assignment. This means that tilde substitution is performed after the = sign and field splitting and file name generation are not performed.

In addition to these built-in reserved command words, ksh93 also uses:

: [ arg . . . ]

The command only expands parameters.

.name [ arg . . . ]

If name is a function defined with the function name reserved word syntax, the function is executed in the current environment (as if it had been defined with the name() syntax.) Otherwise if name refers to a file, the file is read in its entirety and the commands are executed in the current shell environment. The search path specified by PATH is used to find the directory containing the file. If any arguments arg are specified, they become the positional parameters while processing the . command and the original positional parameters are restored upon completion. Otherwise the positional parameters are unchanged. The exit status is the exit status of the last command executed.

See Also

Intro(1), alias(1), break(1), builtin(1), cd(1), chmod(1), csh(1), disown(1), echo(1), exec(1), exit(1), find(1), getoptcvt(1), getopts(1), glob(1), hash(1), history(1), jobs(1), kill(1), ksh(1), ksh93(1), let(1), limit(1), login(1), logout(1), newgrp(1), nice(1), nohup(1), print(1), printf(1), pwd(1), read(1), readonly(1), set(1), sh(1), shift(1), sleep(1), suspend(1), test(1)test(1), test(1B), time(1), times(1), trap(1), typeset(1), umask(1), wait(1), chdir(2), chmod(2), creat(2), umask(2), getopt(3C), profile(4), environ(5)

Name | Description | See Also