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The Bourne shell (sh) is a shell command-line interpreter for computer operating systems.It first appeared on Version 7 Unix, as its default shell. Unix-like systems continue to have /bin/sh—which will be the Bourne shell, or a symbolic link or hard link to a compatible shell—even when other shells are used by most users.
Objections have been raised to both the syntax, how it's typed, and the semantics, how it works.. While easy to type, an important factor for an interactive command processor, the syntax has been criticized as awkward to nest, putting one command substitution inside another, because both the left and the right delimiters are the same. [2]
Evaluate arguments as an expression Version 7 AT&T UNIX false: Shell programming Mandatory Return false value Version 7 AT&T UNIX fc: Misc Optional (UP) Process the command history list fg: Process management Optional (UP) Run jobs in the foreground file: Filesystem Mandatory Determine file type Version 4 AT&T UNIX find: Filesystem Mandatory ...
The bug involved how Bash passed function definitions to subshells through environment variables. [150] The bug had been present in the source code since August 1989 (version 1.03) [151] and was patched in September 2014 (version 4.3). Patches to fix the bugs were made available soon after the bugs were identified.
The first Unix shell was the Thompson shell, sh, written by Ken Thompson at Bell Labs and distributed with Versions 1 through 6 of Unix, from 1971 to 1975. [3] Though rudimentary by modern standards, it introduced many of the basic features common to all later Unix shells, including piping, simple control structures using if and goto , and ...
The term is also used more generally to mean the automated mode of running an operating system shell; each operating system uses a particular name for these functions including batch files (MSDos-Win95 stream, OS/2), command procedures (VMS), and shell scripts (Windows NT stream and third-party derivatives like 4NT—article is at cmd.exe), and ...
The -n option to xargs specifies how many arguments at a time to supply to the given command. The command will be invoked repeatedly until all input is exhausted. Note that on the last invocation one might get fewer than the desired number of arguments if there is insufficient input. Use xargs to break up the input into two arguments per line:
In computer science, a for-loop or for loop is a control flow statement for specifying iteration. Specifically, a for-loop functions by running a section of code repeatedly until a certain condition has been satisfied. For-loops have two parts: a header and a body. The header defines the iteration and the body is the code executed once per ...