When working with an unknown server, the first task of a sys admin is to gather some information about the system, like what OS is it running, what version, what services are running and so on. And there is no single command that can detect distribution specific information consistently across all linux distros.
So in this post we are listing out some common commands that are used to detect distro specific information on linux.
The lsb_release command prints out distribution specific information about a linux distro.
On Ubuntu/debian based systems the command is available by default.
$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 11.04 Release: 11.04 Codename: natty
The lsb_release command is also available on CentOS/Fedora based systems, if the lsb core packages are installed.
# lsb_release -a LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch Distributor ID: CentOS Description: CentOS release 6.4 (Final) Release: 6.4 Codename: Final
2. /etc/*-release files
The /etc directory contains a couple of files that contains information about the distribution. The following files are present on Ubuntu/Debian based systems.
/etc/issue /etc/issue.net /etc/lsb-release /etc/os-release
$ cat /etc/issue Ubuntu 13.10 \n \l $ cat /etc/issue.net Ubuntu 13.10 $ cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=13.10 DISTRIB_CODENAME=saucy DISTRIB_DESCRIPTION="Ubuntu 13.10" $ cat /etc/os-release NAME="Ubuntu" VERSION="13.10, Saucy Salamander" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 13.10" VERSION_ID="13.10" HOME_URL="http://www.ubuntu.com/" SUPPORT_URL="http://help.ubuntu.com/" BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
The file os-release contains a whole lot of information about the system.
CentOS/Fedora based systems contain similar files but with different names.
/etc/centos-release /etc/lsb-release /etc/redhat-release /etc/system-release
# cat /etc/centos-release CentOS release 6.4 (Final) # cat /etc/lsb-release LSB_VERSION=base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch # cat /etc/redhat-release CentOS release 6.4 (Final) # cat /etc/system-release CentOS release 6.4 (Final)
Note that the lsb specific command and files are not present on CentOS by default. The redhat-lsb-core packages have to be installed to make lsb available. The /etc/lsb-release file does not print the distro information in a simple format.
Fedora contains the /etc/os-release file, similar to ubuntu
$ cat /etc/os-release NAME=Fedora VERSION="18 (Spherical Cow)" ID=fedora VERSION_ID=18 PRETTY_NAME="Fedora 18 (Spherical Cow)" ANSI_COLOR="0;34" CPE_NAME="cpe:/o:fedoraproject:fedora:18"
3. cat /proc/version
The /proc/version file contains information about the kernel and some indication about the distro.
On a typical Ubuntu system the contents look like this
$ cat /proc/version Linux version 2.6.38-13-generic ([email protected]) (gcc version 4.5.2 (Ubuntu/Linaro 4.5.2-8ubuntu4) ) #52-Ubuntu SMP Tue Nov 8 16:53:51 UTC 2011
On a typical CentOS system the output looks as follows
# cat /proc/version Linux version 2.6.32-358.11.1.el6.x86_64 ([email protected]) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-3) (GCC) ) #1 SMP Wed Jun 12 03:34:52 UTC 2013
As can be seen above, the version information about the distro is not very clear, although it might be possible to deduce the distro in use.
Output on a RHEL 5 system
# cat /proc/version Linux version 2.6.18-028stab070.14 ([email protected]) (gcc version 4.1.2 20080704 (Red Hat 4.1.2-46)) #1 SMP Thu Nov 18 16:04:02 MSK 2010
4. uname -a
The uname command can also indicate which linux distro is in use, but gives very little information about it.
On Ubuntu, uname can clearly indicate the distribution name.
$ uname -a Linux enlightened-desktop 2.6.38-13-generic #52-Ubuntu SMP Tue Nov 8 16:53:51 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux
However on CentOS, the exact distro name is not revealed.
# uname -a Linux dhcppc3 2.6.32-358.11.1.el6.x86_64 #1 SMP Wed Jun 12 03:34:52 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
Instead it reports the base distro name EL (Redhat).
The following is an attempt to get a portable command for checking distro info across different linux systems.
$ cat /etc/[A-Za-z]*[_-][rv]e[lr]* squeeze/sid DISTRIB_ID=Ubuntu DISTRIB_RELEASE=11.04 DISTRIB_CODENAME=natty DISTRIB_DESCRIPTION="Ubuntu 11.04"
A simpler approach to make a portable command would be like this
$ lsb_release -a || cat /etc/redhat-release || cat /etc/*-release || cat /etc/issue
If one option fails, the command moves to the next one, until one of them works. The above command is not a well tested one and is expected to work fine only on ubuntu/debian and centos/fedora based systems.
Here is another example
$ cat /etc/*-release | uniq -u
That would print all unique lines from all /etc/*-release files. Works well on most distros.