What Is POSIX Shell?

What is POSIX Shell under UNIX / Linux operating systems?

POSIX is an acronym for “Portable Operating System Interface”. POSIX shell is based on the standard defined in Portable Operating System Interface (POSIX) – IEEE P1003.2. It is a set of standards codified by the IEEE and issued by ANSI and ISO. POSIX makes task of cross-platform software development easy. There are various POSIX versions, but the most important are POSIX.1 and POSIX.2, which define system calls and command-line interface.
Tutorial details
Difficulty Easy (rss)
Root privileges No
Requirements None
Time 5m


What is POSIX?

POSIX defines the application programming interface (API), along with Unix command line shells and utility interfaces. This ensure software compatibility with flavors of Unix and other operating systems. The POSIX shell is implemented for many UNIX like operating systems. The POSIX standard is designed to be used by both application programmers and system administrators. Most of the POSIX Shell features are similar to the Korn Shell. The following perating systems are 100% compliant with various POSIX standards:

  • A/UX
  • AIX
  • HP-UX
  • IRIX
  • OS X
  • QNX
  • Solaris
  • Tru64
  • UnixWare

Please note that GNU/Linux (most distributions) and *BSD operating systems are not officially certified as POSIX compatible, but comply in large part. For more information see the following ulrs:

  1. A joint technical committee of ISO and IEC – POSIX page
  2. POSIX page at opengroup.org
🐧 Get the latest tutorials on SysAdmin, Linux/Unix, Open Source/DevOps topics:
CategoryList of Unix and Linux commands
File Managementcat
FirewallAlpine Awall CentOS 8 OpenSUSE RHEL 8 Ubuntu 16.04 Ubuntu 18.04 Ubuntu 20.04
Network Utilitiesdig host ip nmap
OpenVPNCentOS 7 CentOS 8 Debian 10 Debian 8/9 Ubuntu 18.04 Ubuntu 20.04
Package Managerapk apt
Processes Managementbg chroot cron disown fg jobs killall kill pidof pstree pwdx time
Searchinggrep whereis which
User Informationgroups id lastcomm last lid/libuser-lid logname members users whoami who w
WireGuard VPNAlpine CentOS 8 Debian 10 Firewall Ubuntu 20.04

0 comments… add one

Leave a Reply

Your email address will not be published.

Use HTML <pre>...</pre>, <code>...</code> and <kbd>...</kbd> for code samples.