awk & Sed

Posted on December 22, 2008 by admin

Calculate sum of the file size

ls -l access_log.2008-12-20*|gawk ‘{a+=$5;} END {print a;}’

Edit special lines using regular expression

awk ‘/aaa/ ‘ filename

Change file names using sed

##Example: from access_log.2008-12-20.01.gz.1 to access_log.2008-12-20.01.1.gz

for file in `ls access_log.2008-12-20.*`

newname=`echo $file|sed ‘s/$access_log.2008-12-20.[0-9][0-9]$.gz.$[0-9]*$/\1.\2.gz/’`

size=`ls -l $file|awk ‘{print $5}’`

if [ $size -gt 100 ];then

echo “$file-> $newname”

mv -v $file $newname

done

bash — if

Posted on November 12, 2008 by admin

#!/bin/bash

if [ -n “$1” ]; then
filename = $1;
else
filename = `date –date=’1 hour ago’ “+%Y-%m-%d.%H”`;
fi

Compare numbers with -gt -lt -ne -eq

if [ “${size}” -gt 100 ];then
echo $size
fi

Compare strings with = !=

if [ “${domain}” = “lalife.net” ];then
echo “correct”
fi
(#if [ “${domain}”=”lalife.net” ];then (##this won’t work without space around “=” or “!=”)

When using [[ ]]
if [[ ${domain} = “lalife.net” ]];then
echo “correct”
fi

([ ] needs the variable to be inside of “”)

Match
if [[ ${domain} =~ “lalife.net” ]];then
echo “correct”
fi
([ ] doesn’t work with =~)