stephenb linux geek. foodie. libertarian. mobile addict.

Using getops with Bash

Getopts is an easy tool to process and check your command line arguments in a bash script. Far easier than trying to parse out the options yourself!

Example script:

#!/bin/bash
# Example script using getops
usage () {
cat << EOF
Example Script

usage: $0 options

        -h     Display this message
        -v     Patch Version
        -s     Remote server to patch

EOF
}

while getopts "hv:s:" OPTION
do
     case $OPTION in
         h)
             usage
             exit 1
             ;;
        v)
             VERSION=$OPTARG
             ;;
        s)
            HOST=$OPTARG
             ;;
        esac
done

if [[ ! -z $VERSION ]] && [[ ! -z $HOST ]]
then
        echo "You selected $VERSION to be applied to $HOST!"
else
        echo "You didn't tell me what to do."
        usage
        exit 1
fi

exit

Grep and Multiline Regular Expressions

Nothing new here: needed to go through some old log files to find something. Unfortunately, I needed to match across 2 lines specifically. I wrote up my regex, and tested it in Reggy and all was good.  I tried it out in the real world but didn't get any matches.  GNU Grep and Egrep don't support \n! It only searches one line at a time.  Enter: pcregrep -M.

(The other catch is that the files are compressed.  bzcat and zcat solve this problem.)

The entry I was looking for:

I 23:21:37:465  aaaaaaa  ZzzHandler: Subscription expired for x.
D 23:21:37:466  aaaaaaa  ZzzHandler: Proceeding to deactivate account

So I came up with this obfuscated 'for' loop:

for i in $(find /mnt/xxxxxxx -name xxxxxxx*bz2 -type f -print)
do
            echo $i; bzcat $i | \
            pcregrep -M ".*ZzzHandler: Subscription expired.*\n.*Proceeding to deactivate.*"
done | tee -a /tmp/xxxxxx-archived.log