Listing 6: mxfl -- Improved standalone program to prune files

:
######################################################
# mxfl - maximum file length
######################################################

test $# = 2 || {
echo "usage: `basename $0` [filename] [maxlines]"
xstatus=1
exit 1
}

xstatus=0

# always cleanup
trap 'rm -f $tmpfile; exit $xstatus' 0 1 2 3 15

# if anything unusual happens, stop
set -e

test -f $1 || {
echo "Error: could not find: $1"
xstatus=2
exit 2
}
tmpfile=/tmp/mxfl.$$

# use tail to grab the last few lines. if
# things are ok, then cat the grabbed lines
# into the source file.  cat is used because
# it leaves the ownership and permissions unchanged.

tail -${2} $1 > $tmpfile && cat $tmpfile > $1
xstatus=$?