Advanced Bash−Scripting Guide

for planet in "Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto"
do
echo $planet
done
exit 0
Advanced Bash−Scripting Guide
Each [list] element may contain multiple parameters. This is useful when
processing parameters in groups. In such cases, use the set command (see Example
11−13) to force parsing of each [list] element and assignment of each component
to the positional parameters.
Example 10−2. for loop with two parameters in each [list] element
#!/bin/bash
# Planets revisited.
# Associate the name of each planet with its distance from the sun.
for planet in "Mercury 36" "Venus 67" "Earth 93" "Mars 142" "Jupiter 483"
do
set −− $planet # Parses variable "planet" and sets positional parameters.
# the "−−" prevents nasty surprises if $planet is null or begins with a dash.
# May need to save original positional parameters, since they get overwritten.
# One way of doing this is to use an array,
# original_params=("$@")
echo "$1
$2,000,000 miles from the sun"
#−−−−−−−two tabs−−−concatenate zeroes onto parameter $2
done
# (Thanks, S.C., for additional clarification.)
exit 0
A variable may supply the [list] in a for loop.
Example 10−3. Fileinfo: operating on a file list contained in a variable
#!/bin/bash
# fileinfo.sh
FILES="/usr/sbin/privatepw
/usr/sbin/pwck
/usr/sbin/go500gw
/usr/bin/fakefile
/sbin/mkreiserfs
/sbin/ypbind"
echo
for file in $FILES
do
# List of files you are curious about.
# Threw in a dummy file, /usr/bin/fakefile.
Chapter 10. Loops and Branches 104