Change upper case to lower case
#echo ‘TEST’|/usr/bin/tr -s ‘[:upper:]’ ‘[:lower:]’
test
Work with array
IFS=$’\n’ ##here tells how to devide the output, default is space
##but I want to put each line into a array
files=($(ls ./) ##put file names into an array using ()
for (( i=0;i<${#files[@]};i++ ));do mv $files[$i] $files[$i]_OLD done
Match pattern
if [[ $string =~ “data” ]];do
echo “$string contains data”
done
Very good page for logrotate usage and examples
HowTo: The Ultimate Logrotate Command Tutorial with 10 Examples
Force logrotate to run,
logrotate -f /etc/logrotate.d/app.conf
To avoid files started with “.” in find result
find . -name ‘.snapshot’ -prune -o -name ‘file.mp4’
To delete files older than 7*24h
find /var/tmp -mtime +7 -exec rm -f {} \;
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.*`
do
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”
fi
mv -v $file $newname
done
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
Compare strings with = !=
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 =~)