FAQ Updates – June/26/2011

Posted on in Categories Sys admin last updated June 26, 2011

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Shell script to watch the disk space

Posted on in Categories Howto, Linux, Monitoring, Shell scripting last updated August 16, 2007

df displays the amount of disk space available on the file system containing each file name argument. If no file name is given, the space available on all currently mounted file systems is shown. Read man page of df if you are new to df command.


=> Find disk space using df

=> Filter out filesystem and find out the percentage of space using grep

=> Write a shell script

Step # 1: First get disk space:

$ df -H


Filesystem             Size   Used  Avail Use% Mounted on
/dev/hdb1               20G    14G   5.5G  71% /
tmpfs                  394M   4.1k   394M   1% /dev/shm
/dev/hdb5               29G    27G   654M  98% /nas/www

Step # 2: Next filter out filesystem and find out the percentage of space

$ df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }'


71% /dev/hdb1
98% /dev/hdb5

Step # 3: Write a shell script

Above command displays field 5 and 1 of df command. Now all you need to do is write a script to see if the percentage of space is >= 90% (download script):

df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
  echo $output
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
  if [ $usep -ge 90 ]; then
    echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)" |
     mail -s "Alert: Almost out of disk space $usep%" [email protected]

Setup Cron job

Save and install script as cronjob. Copy script to /etc/cron.daily/ (script downolad link)
# cp diskAlert /etc/cron.daily/
# chmod +x /etc/cron.daily/diskAlert

OR install as cronjob:
crontab -e

Write cronjob as per your requirement
10 0 * * * /path/to/diskAlert

Updated script version

Tony contributed and updated my script – You can exclude selected filesystem in case you don’t want monitor all filesystems.

# set -x
# Shell script to monitor or watch the disk space
# It will send an email to $ADMIN, if the (free available) percentage of space is >= 90%.
# -------------------------------------------------------------------------
# Set admin email so that you can get email.
# set alert level 90% is default
# Exclude list of unwanted monitoring, if several partions then use "|" to separate the partitions.
# An example: EXCLUDE_LIST="/dev/hdd1|/dev/hdc5"
function main_prog() {
while read output;
#echo $output
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1)
  partition=$(echo $output | awk '{print $2}')
  if [ $usep -ge $ALERT ] ; then
     echo "Running out of space \"$partition ($usep%)\" on server $(hostname), $(date)" | \
     mail -s "Alert: Almost out of disk space $usep%" $ADMIN

if [ "$EXCLUDE_LIST" != "" ] ; then
  df -H | grep -vE "^Filesystem|tmpfs|cdrom|${EXCLUDE_LIST}" | awk '{print $5 " " $6}' | main_prog
  df -H | grep -vE "^Filesystem|tmpfs|cdrom" | awk '{print $5 " " $6}' | main_prog

Linux command to gathers up information about a Linux system

Posted on in Categories CentOS, Debian Linux, Gentoo Linux, Howto, Linux, Networking, RedHat/Fedora Linux, Sys admin, Tips, Ubuntu Linux last updated August 2, 2007

If you are developing an application for Linux desktop and would like to automatically find out more information about system, use the following commands in shell scripts to gather information about system. Recently I was involved in project where I need to collect information about running GUI, browser and other information such as disk space, running kernel etc.

Find out KDE Desktop version:

konqueror --version

Find out Gnome Desktop version:

gnome-panel --version

Find out Mozilla browser version:

mozilla --version

Find out Firefox browser version:

firefox --version

Find out current Language:

set | egrep '^(LANG|LC_)'

Find out disk space usage:

df -h

Find/Estimate file space usage:

du -h

Find out version of Linux glibc:

ls -l /lib/libc-*.so /lib/libc.so*

Find out user limits:

ulimit -a

Find out installed device drivers (modules)


Find out information about an X server:


It can find out:

  • Name of display:
  • Version number
  • Vendor name (such as The XFree86 Project)
  • Vendor release number
  • And XFree86 version number

Find out information about Linux CPU

cat /proc/cpuinfo

Find out information about Linux Memory

cat /proc/meminfo


free -m


free -g

Find out user shell name:

ps -p $$ | tail -1 | awk '{ print $4 }'

Dump Linux kernel variables

/sbin/sysctl -a

Find out running Linux kernel version:

uname -mrs
uname -a
cat /proc/version

Dump or display memory information and swap information:

free -m

Network card and IP address information:

ifconfig -a
ifconfig -a|less

Debian / Ubuntu Linux network configuration file (all interface eth0,eth1,…ethN)

more /etc/network/interfaces

Redhat / CentOS / Fedora Linux network configuration file (eth0)

more  /etc/sysconfig/network-scripts/ifcfg-eth0

Note replace eth1 for 2nd network card and so on.

Display routing information

route -n

Display list of all open ports

netstat -tulpn

View login related logs

tail -f /var/log/secure
vi /var/log/secure
grep 'something' /var/log/secure

View mail server related logs

tail -f /var/log/maillog
vi /var/log/maillog
grep 'something' /var/log/maillog

Find how long the system has been running


Show who is logged on and what they are doing


Display list of tasks


Display all running process

ps aux
ps aux | grep process-name

Display list of all installed software on Redhat / CentOS / Fedora

rpm -qa
rpm -qa | grep 'software-name'
rpm -qa | less

Display list of all installed software on Debian / Ubuntu

dpkg --list

Once information collected it can be easily send as an email to help desk. You can use all above command to gathers information about a remote Linux system over secure ssh session (see related functions that gathers up information about a Linux and FreeBSD system). Best part is all above commands runs in non privileged mode.