Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
first_param=$1
second_param=$2
shift; shift # Shift past first two positional params.
remaining_params="$*"
echo
echo "first parameter = $first_param"
echo "second parameter = $second_param"
echo "remaining parameters = $remaining_params"
# one
# two
# three four five
echo; echo
# Again.
set −− $variable
first_param=$1
second_param=$2
echo "first parameter = $first_param"
echo "second parameter = $second_param"
# one
# two
# ======================================================
set −−
# Unsets positional parameters if no variable specified.
first_param=$1
second_param=$2
echo "first parameter = $first_param"
echo "second parameter = $second_param"
# (null value)
# (null value)
exit 0
unset
See also Example 10−2 and Example 12−40.
The unset command deletes a shell variable, effectively setting it to null. Note that this command
does not affect positional parameters.
bash$ unset PATH
bash$ echo $PATH
bash$
Example 11−15. "unsetting" a variable
#!/bin/bash
# unset.sh: Unsetting a variable.
variable=hello
echo "variable = $variable"
# Initialized.
unset variable
# Unset.
# Same effect as variable=
echo "(unset) variable = $variable" # $variable is null.
export
exit 0
Chapter 11. Internal Commands and Builtins 136