Linux command to gathers up information about a Linux system

last updated in Categories CentOS, Debian Linux, Gentoo Linux, Howto, Linux, Networking, RedHat/Fedora Linux, Sys admin, Tips, Ubuntu Linux

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)

lsmod

Find out information about an X server:

xdpyinfo

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

OR

free -m

OR

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
route

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

uname
w

Show who is logged on and what they are doing

w
who

Display list of tasks

top

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.

Running Commands on a Remote Linux / UNIX Host

last updated in Categories CentOS, Debian Linux, FreeBSD, Gentoo Linux, Howto, HP-UX, Linux, Monitoring, Networking, OpenBSD, OS X, RedHat/Fedora Linux, Security, Shell scripting, Solaris, Tips, Ubuntu Linux, UNIX

You would like to execute a command on a remote Linux/FreeBSD/Solaris/UNIX host and have the result displayed locally. Once result obtained it can be used by local script or program. A few examples:
=> File system and disk information

=> Get user information

=> Find out all running process

=> Find out if particular service is running or not etc

You can use rsh or ssh for this purpose. However, for security reason you should always use the ssh and NOT rsh. Please note that remote system must run the OpenSSH server.

Syntax for running command on a remote host:
ssh [USER-NAME]@[REMOTE-HOST] [command or script]

Where,

  • ssh: ssh (SSH client) is a program for logging into a remote machine and for executing commands on a remote machine.
  • USER-NAME: Remote host user name.
  • REMOTE-HOST: Remote host ip-address or host name, such as fbsd.cyberciti.biz.
  • command or script: Command or shell script is executed on the remote host instead of a login shell.

Examples

(A) Get disk information from a server called www1.cyberciti.biz:
$ ssh vivek@www1.cyberciti.biz df -h

(B) List what ports are open on remote host
$ ssh vivek@www1.cyberciti.biz netstat -vatn

(C) Reboot remote host:
$ ssh root@www1.cyberciti.biz reboot

(D) Restart mysql server (please note enclosed multiple command line arguments using a single or double quotes)
$ ssh root@www1.cyberciti.biz '/etc/init.d/mysql restart'

(E) Get memory information and store result/output to local file /tmp/memory.status:
$ ssh vivek@www1.cyberciti.biz 'free -m' > /tmp/memory.status

(G) You can also run multiple command or use the pipes, following command displays memory in format of “available memory = used + free memory” :
$ ssh vivek@debian.test.com free -m | grep "Mem:" | awk '{ print "Total memory (used+free): " $3 " + " $4 " = " $2 }'

See how to configure ssh for password less login using public key based authentication.

=> Related: shell script to get uptime, disk usage, cpu usage, RAM usage,system load,etc. from multiple Linux servers and output the information on a single server in a html format.