UNIX for Dummies Questions & Answers

#!/bin/bash
#Script to remove line that contains a pattern
echo "Usage: $0 PATTERNTOREMOVE INPUTFILE [OUTPUTFILE]"

if [ $# \< 2 ]; then exit; fi
#if less than two arguments, exit script

if  [ $# = 3 ] ; then
#if 3 args, then third is the output filename
        OFILE=$3;

elif [ $# = 2 ] ; then
#if 2 args then input is also output
#but a temp file is needed
        OFILE="$2"new;

else echo Too many arguments!!!;
        exit;
fi

#output all lines that DO NOT contain string to file
grep -v $1 $2 >$OFILE


if [ $# = 2 ]; then
#if only 2 args rename temp file to input filename
mv "$2"new $2;

fi