Purge Removed packages

Packages marked as rc by dpkg mean that the configuration files are not yet removed. The following command will purge them:

dpkg --list |grep "^rc" | cut -d " " -f 3 | xargs -r sudo dpkg --purge

How to permanently delete ALL older kernels

This script will remove ALL versions but two, the currently active and the most recent of the remaining installed versions:

#/bin/bash
keep=2
ls /boot/ | grep vmlinuz | sed 's@vmlinuz-@linux-image-@g' | grep -v $(uname -r) | sort -Vr | tail -n +$keep | while read I
do
    aptitude purge -y $I
done
update-grub

you can specify how many kernels to keep by adjusting the keep variable, if you set it to 1, only the active kernel will be left installed.

Or you can do it in one line:

ls /boot/ | grep vmlinuz | sed 's@vmlinuz-@linux-image-@g' | grep -v $(uname -r) | sort -Vr | tail -n +2 | xargs -r sudo aptitude purge -y

that you can use in crontab.

IPTables debugging

The following command will only show rules that have the action set to DROP or REJECT and omit the rules that didn't had any matches:

watch -n1 "iptables -nvL | grep -i 'DROP\|REJECT\' | egrep -v '^\s*0\s*0'"

This one does the same but with some colour highlighting, it will only show rules with matches, the words DROP and REJECT will appear in red and the word ACCEPT will be in green:

watch --color -n1 "iptables -nvL | egrep -v '^\s*0\s*0' | sed 's/\(DROP\|REJECT\)/\x1b[49;31m\1\x1b[0m/g' | sed 's/\(ACCEPT\)/\x1b[49;32m\1\x1b[0m/g'"

File rotator script

This is a script that I use to rotate some logs, the commented lines will tell you what it does exactly:

#!/bin/sh
#-----------------------------------------------------------------------
# FILE ROTATOR SCRIPT
#
# The purpose of this script is to rotate, compress and delete files
# - Files older than ARC_AGE are gzipped and rotated
# - Files bigger than SIZE_LIM are gzipped and rotated
# - Gzipped files older than DEL_AGE are deleted
#
#-----------------------------------------------------------------------
# Vars
DATE=`date +%F"-"%H:%M`
FILEDIR="/storage/logs/"
DEL_AGE="30"
ARC_AGE="1"
SIZE_LIM="20M"
# Diagnostics
echo "-= Rotation starting =-"
echo "    Directory to search: $FILEDIR"
echo "    File age to check for delition: $DEL_AGE"
echo "    File age to check for archive: $ARC_AGE"
echo "    File size to check for archive: $SIZE_LIM"
echo " "
# Compress all unconpressed files which last modification occured more than ARC_AGE days ago
echo "-= Looking for old files =-"
FILES=`find $FILEDIR -type f -mtime +$ARC_AGE -not \( -name '*.gz' \) -print`
echo "Files to be archived:"
echo $FILES
echo " "
for FILE in $FILES; do
    # Compress but keep the original file
    gzip -9 -c "$FILE" > "$FILE".$DATE.gz;
    # Check if file is beeing used:
    lsof $FILE
    ACTIVE=$?
    # Delete inactive files, truncate if active
    if [ $ACTIVE != 0 ]; then
        # Delete the file
        rm "$FILE";
    else
        # Truncate file to 0
        :>"$FILE";
    fi
done
# Compress all unconpressed files that are bigger than SIZE_LIM
echo "-= Looking for big files =-"
FILES=`find $FILEDIR -type f -size +$SIZE_LIM -not \( -name '*.gz' \) -print`
echo "Files to be archived:"
echo $FILES
echo " "
for FILE in $FILES; do
    # Compress but keep the original file
    gzip -9 -c "$FILE" > "$FILE".$DATE.gz;
    # Truncate original file to 0
    :>"$FILE";
done
echo "-= Deleting old archived files =-"
FILES_OLD=`find $FILEDIR -type f -mtime +$DEL_AGE -name '*.gz' -print`
echo "Archived files older than $DEL_AGE days to be deleted:"
echo $FILES_OLD
echo " "
# Deletes old archived files.
find $FILEDIR -type f -mtime +$DEL_AGE -name '*.gz' -exec rm -f {} \;
echo "-= Rotation completed =-"
echo " "

Rename files from upper case filename to lower case

The following one line script will rename every file (in the current folder) to lowercase:

for i in *; do mv $i `echo $i | tr [:upper:] [:lower:]`; done