binsh

binsh refers to the executable located at /bin/sh, the standard shell on many Unix-like systems. It is the primary command interpreter used for both interactive command input and the execution of shell scripts. In practice, /bin/sh is a POSIX-compliant shell designed to provide a portable and predictable scripting environment across different systems. The implementation behind /bin/sh varies: it is commonly a symbolic link to another shell such as dash, bash, ash, or ksh. The choice of actual program depends on the operating system and the distribution’s configuration. The POSIX specification for the shell defines a minimal syntax and built-in utilities intended to be portable; many shells provide additional extensions that are not guaranteed by POSIX and should be avoided for portable scripts.

Scripts that aim for portability often begin with a shebang line like #!/bin/sh, signaling that they should be executed by the system’s /bin/sh. POSIX features include simple command substitution, redirection, loops, conditionals, and arithmetic with shell built-ins. Non-POSIX features, such as certain array or word-splitting behaviors found in other shells, can cause scripts to fail when run under /bin/sh.

System maintenance, startup scripts, and package managers frequently assume the presence of a usable /bin/sh, making it a foundational component of the user environment. See also: Bourne shell, POSIX, dash, Bash, ash.