Admin - Fu

Kill all processes belonging to a user

ps wwwwuax|awk '/command/ { printf("kill -9 %s\n",$2) }'|/bin/sh

Remove all at jobs

atq | sed 's_\([0-9]\{1,8\}\).*_\1_g' | xargs atrm

Display the top ten running processes - sorted by memory usage

  ps aux | sort -nk +4 | tail

Slow down IO heavy process

  slow () { 
      [ -n $1 ] && \
      while ps -p $1 >/dev/null ; do 
          kill -STOP  $1
          sleep 1
          kill -CONT $1
          sleep 1
      done &
  }

Extract list of packages installed on one server and generate ‘apt’ command to install them on a new server

  dpkg --list | rgrep ii | cut -d" " -f3 | sed ':a;N;$!ba;s/\n/ /g' | \
      sed 's/^\(.\)/apt-get install \1/'

Display a list of RPMs installed on a particular date

rpm -qa --queryformat '%{installtime}  \"%{vendor}\" \
    %{name}-%{version}-%{release}  %{installtime:date}\n' | grep "Thu 05 Mar"

Display installed RPMs in size order, largest first

rpm -qa --queryformat '%{size} %{name}-%{version}-%{release}\n' | \
    sort -k 1,1 -rn | nl

Create an emergency swapfile when the existing swap space is getting tight

sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024000
sudo mkswap /swapfile
sudo swapon /swapfile