Advanced Bash−Scripting Guide

This line occurs three times.
This line occurs three times.
This line occurs three times.
Advanced Bash−Scripting Guide
bash$ uniq −c testfile
1 This line occurs only once.
2 This line occurs twice.
3 This line occurs three times.
bash$ sort testfile | uniq −c | sort −nr
3 This line occurs three times.
2 This line occurs twice.
1 This line occurs only once.
The sort INPUTFILE | uniq −c | sort −nr command string produces a frequency of
occurrence listing on the INPUTFILE file (the −nr options to sort cause a reverse numerical sort).
This template finds use in analysis of log files and dictionary lists, and wherever the lexical structure
of a document needs to be examined.
Example 12−8. Word Frequency Analysis
#!/bin/bash
# wf.sh: Crude word frequency analysis on a text file.
# Check for input file on command line.
ARGS=1
E_BADARGS=65
E_NOFILE=66
if [ $# −ne "$ARGS" ] # Correct number of arguments passed to script?
then
echo "Usage: `basename $0` filename"
exit $E_BADARGS
fi
if [ ! −f "$1" ] # Check if file exists.
then
echo "File \"$1\" does not exist."
exit $E_NOFILE
fi
########################################################
# main ()
sed −e 's/\.//g' −e 's/ /\
/g' "$1" | tr 'A−Z' 'a−z' | sort | uniq −c | sort −nr
# =========================
# Frequency of occurrence
# Filter out periods and
#+ change space between words to linefeed,
#+ then shift characters to lowercase, and
#+ finally prefix occurrence count and sort numerically.
########################################################
Chapter 12. External Filters, Programs and Commands 161