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Build-In Commands
Some command are build into the shell and
others are "external executables" on the system.
A selection of build-in commands:
- eval arg ... :
Executes args as a line of shell script.
- exec command:
Begins executing command under the same process
ID as the current script and never returns.
This is most often used for ``wrapper'' scripts,
which exec the real program binary as its last line.
- local var =value:
Assigns a value to a variable,visible only
within the current function.
- pushd directory and popd:
For jumping around in a stack of directories.
- printf format args ... :
This is like the C printf function, useful
for more complex formatting of output.
See printf(3) (man 3 printf) for details.
- unset VAR :
Deletes a variable or environment variable.
unset -f func deletes a function.
- wait:
wait Pauses until all background jobs have completed.
wait PID pauses until background process with
process ID of PID has exited and returns its exit code.