Advanced Bash−Scripting Guide

Advanced Bash−Scripting Guide
day=$?
strip_leading_zero $month
month=$?
day_index $day $month $year
date2=$?
abs $date2
date2=$value
# Make sure it's positive.
calculate_difference $date1 $date2
abs $diff
diff=$value
# Make sure it's positive.
echo $diff
exit 0
# Compare this script with the implementation of Gauss' Formula in C at
# http://buschencrew.hypermart.net/software/datedif
Example A−9. Make a "dictionary"
#!/bin/bash
# makedict.sh [make dictionary]
# Modification of /usr/sbin/mkdict script.
# Original script copyright 1993, by Alec Muffett.
#
# This modified script included in this document in a manner
#+ consistent with the "LICENSE" document of the "Crack" package
#+ that the original script is a part of.
# This script processes text files to produce a sorted list
#+ of words found in the files.
# This may be useful for compiling dictionaries
#+ and for lexicographic research.
E_BADARGS=65
if [ ! −r "$1" ]
then
echo "Usage: $0 files−to−process"
exit $E_BADARGS
fi
# Need at least one
#+ valid file argument.
# SORT="sort" # No longer necessary to define options
#+ to sort. Changed from original script.
cat $* |
# Contents of specified files to stdout.
tr A−Z a−z |
# Convert to uppercase.
tr ' ' '\012' |
# New: change spaces to newlines.
# tr −cd '\012[a−z][0−9]' | # Get rid of everything non−alphanumeric
#+ (original script).
tr −c '\012a−z' '\012' | # Rather than deleting
#+ now change non−alpha to newlines.
sort |
# $SORT options unnecessary now.
uniq |
# Remove duplicates.
Appendix A. Contributed Scripts 376