Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
if [ ! −e "$file" ] # Check if file exists.
then
echo "$file does not exist."; echo
continue
# On to next.
fi
ls −l $file | awk '{ print $9 "
whatis `basename $file` # File info.
echo
done
file size: " $5 }' # Print 2 fields.
exit 0
The [list] in a for loop may contain filename globbing, that is, using wildcards for filename
expansion.
Example 10−4. Operating on files with a for loop
#!/bin/bash
# list−glob.sh: Generating [list] in a for−loop using "globbing".
echo
for file in *
do
ls −l "$file" # Lists all files in $PWD (current directory).
# Recall that the wild card character "*" matches every filename,
# however, in "globbing", it doesn't match dot−files.
# If the pattern matches no file, it is expanded to itself.
# To prevent this, set the nullglob option
# (shopt −s nullglob).
# Thanks, S.C.
done
echo; echo
for file in [jx]*
do
rm −f $file # Removes only files beginning with "j" or "x" in $PWD.
echo "Removed file \"$file\"".
done
echo
exit 0
Omitting the in [list] part of a for loop causes the loop to operate on $@, the list of arguments
given on the command line to the script. A particularly clever illustration of this is Example A−17.
Example 10−5. Missing in [list] in a for loop
#!/bin/bash
# Invoke both with and without arguments, and see what happens.
Chapter 10. Loops and Branches 105