shell_builtins(1)

NAME | DESCRIPTION | SEE ALSO

NAME

shell_builtins- shell command interpreter built-in functions

DESCRIPTION

The shell command interpreters sh(1), csh(1), and ksh(1) have special built-in functions which are interpreted by the shell as commands. Many of these built-in commands are implemented by more than one of the shells, and some are unique to a particular shell. These are:

command	built into
alias	csh, ksh
bg	csh, ksh, sh
break	csh, ksh, sh
case	csh, ksh, sh
cd	csh, ksh, sh
chdir	csh, sh
continue	csh, ksh, sh
dirs	csh
echo	csh, ksh, sh
eval	csh, ksh, sh
exec	csh, ksh, sh
exit	csh, ksh, sh
export	ksh, sh
fc	ksh
fg	csh, ksh, sh
for	ksh, sh
foreach	csh
function	ksh
getopts	ksh, sh
glob	csh
goto	csh
hash	ksh, sh
hashstat	csh
history	csh
if	csh, ksh, sh
jobs	csh, ksh, sh
kill	csh, ksh, sh
let	ksh
limit	csh
login	csh, ksh, sh
logout	csh, ksh, sh
nice	csh
newgrp	ksh, sh
notify	csh
onintr	csh
popd	csh
print	ksh
pushd	csh
pwd	ksh, sh
read	ksh, sh
readonly	ksh, sh
rehash	csh
repeat	csh
return	ksh, sh
select	ksh
set	csh, ksh, sh
setenv	csh
shift	csh, ksh, sh
source	csh
stop	csh, ksh, sh
suspend	csh, ksh, sh
switch	csh
test	ksh, sh
time	csh
times	ksh, sh
trap	ksh, sh
type	ksh, sh
typeset	ksh
ulimit	ksh, sh
umask	csh, ksh, sh
unalias	csh, ksh
unhash	csh
unlimit	csh
unset	csh, ksh, sh
unsetenv	csh
until	ksh, sh
wait	csh, ksh, sh
whence	ksh
while	sh, ksh, 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.

Additional 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. Additional 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.

Additional 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 given, 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.

SEE ALSO

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

SunOS 5.8  Last Revised 1 Feb 1995

NAME | DESCRIPTION | SEE ALSO