Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
for a
do
echo −n "$a "
done
# The 'in list' missing, therefore the loop operates on '$@'
#+ (command−line argument list, including whitespace).
echo
exit 0
It is possible to use command substitution to generate the [list] in a for loop. See also Example
12−39, Example 10−10 and Example 12−33.
Example 10−6. Generating the [list] in a for loop with command substitution
#!/bin/bash
# A for−loop with [list] generated by command substitution.
NUMBERS="9 7 3 8 37.53"
for number in `echo $NUMBERS` # for number in 9 7 3 8 37.53
do
echo −n "$number "
done
echo
exit 0
This is a somewhat more complex example of using command substitution to create the [list].
Example 10−7. A grep replacement for binary files
#!/bin/bash
# bin−grep.sh: Locates matching strings in a binary file.
# A "grep" replacement for binary files.
# Similar effect to "grep −a"
E_BADARGS=65
E_NOFILE=66
if [ $# −ne 2 ]
then
echo "Usage: `basename $0` string filename"
exit $E_BADARGS
fi
if [ ! −f "$2" ]
then
echo "File \"$2\" does not exist."
exit $E_NOFILE
fi
for word in $( strings "$2" | grep "$1" )
Chapter 10. Loops and Branches 106