tl;dr

• Use the uname command
• Use the /etc/*-release files
• Use a programming language (high-level approach) python -mplatform
• Use environment variables like $OSTYPE

uname, hostname, machine, sw_vers are all commands you can use.

uname

uname prints operating system name.

• CentOS, Ubuntu: Linux
• Mac OS X: Darwin

CentOS

uname flags

• uname has a few flags (a,p,m) you can use.
  • uname : with no arguments will name the operating system.
  • uname -a : check kernel version and system architecture
  • uname -m : will give the “machine hardware name”. Tells whether your system is 32-bit or 64-bit
  • -n : print the nodename (the nodename may be a name that the system is known by to a communications network).
  • uname -p : processor type, but is usually unknown on modern Unix platforms. prints the machine processor architecture name.
  • uname -r : print the operating system release.
  • uname -s : print the operating system name.
  • unae -v : print the operating system version.

cat /etc/ files

• cat /etc/issue : check CentOS/Ubuntu version
• cat /etc/os-release : get distro name 2
• cat /etc/lsb-release :
• cat /etc/redhat-release :

hostname : check hostname /bin/arch/ : if it exists, will usually give the type of processor. echo $OSTYPE : env variable that stores OS name python -mplatform :

cat /etc/issue

$ cat /etc/issue
Ubuntu 14.04.3 LTS \n \l

cat /etc/os-release 2

Most major distros are moving towards a system where they use /etc/os-release to store this information. Most modern distributions also include the lsb_release tools but these are not always installed by default.

Ubuntu

cat /etc/os-release

NAME="Ubuntu"
VERSION="14.04.3 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.3 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"

Doesn’t work on CentOS or OSX it seems.

cat /etc/lsb-release

Ubuntu

cat /etc/lsb-release

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.04
DISTRIB_CODENAME=trusty
DISTRIB_DESCRIPTION="Ubuntu 14.04.3 LTS"

cat /etc/redhat-release

CentOS

cat /etc/redhat-release

CentOS release 6.7 (Final)

CentOS actually shows 3 release file names. The other two /etc/redhat-release and /etc/system-release are symlinks to /etc/centos-release.

ls -alhs /etc/*-release

-rw-r--r-- 1 root root 27 Aug  3 12:12 /etc/centos-release
lrwxrwxrwx 1 root root 14 Aug  7 12:02 /etc/redhat-release -> centos-release
lrwxrwxrwx 1 root root 14 Aug  7 12:02 /etc/system-release -> centos-release

Release files

Find and cat the release files. The following commands lists all *-release files in the /etc/ folder.

ls -alhs /etc/*-release

• /etc/lsb-release (Ubuntu)
• /etc/os-release (Ubuntu)
• /etc/centos-release (CentOS)
• /etc/redhat-release -> centos-release (CentOS)
• /etc/system-release -> centos-release (CentOS)

$OSTYPE link

The bash manpage says that the variable OSTYPE stores the name of the operation system:

OSTYPE Automatically set to a string that describes the operating system on which bash is executing. The default is system- dependent.

• For OS X El Capitan 10.11.1 $OSTYPE is darwin15
• For Ubuntu 14.04.3 LTS $OSTYPE is linux-gnu

python -mplatform

python -mplatform

# Ubuntu
Linux-3.13.0-68-generic-x86_64-with-Ubuntu-14.04-trusty

# CentOS
Linux-2.6.32-042stab108.6-i686-with-centos-6.7-Final

# Mac OS X
Darwin-15.0.0-x86_64-i386-64bit

# Armbian
Linux-3.4.113-sun8i-armv7l-with-Ubuntu-16.04-xenial