Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
exit 0
See also Example 26−9, Example 26−10, and Example A−7.
−−−
Now, a for−loop used in a "real−life" context.
Example 10−13. Using efax in batch mode
#!/bin/bash
EXPECTED_ARGS=2
E_BADARGS=65
if [ $# −ne $EXPECTED_ARGS ]
# Check for proper no. of command line args.
then
echo "Usage: `basename $0` phone# text−file"
exit $E_BADARGS
fi
if [ ! −f "$2" ]
then
echo "File $2 is not a text file"
exit $E_BADARGS
fi
fax make $2
# Create fax formatted files from text files.
for file in $(ls $2.0*) # Concatenate the converted files.
# Uses wild card in variable list.
do
fil="$fil $file"
done
efax −d /dev/ttyS3 −o1 −t "T$1" $fil
# Do the work.
# As S.C. points out, the for−loop can be eliminated with
# efax −d /dev/ttyS3 −o1 −t "T$1" $2.0*
# but it's not quite as instructive [grin].
while
exit 0
This construct tests for a condition at the top of a loop, and keeps looping as long as that condition is
true (returns a 0 exit status). In contrast to a for loop, a while loop finds use in situations where the
number of loop repetitions is not known beforehand.
while [condition]
do
command...
done
Chapter 10. Loops and Branches 110