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tcsh and sh shell windows on a Mac OS X Leopard [1] desktop. A Unix shell is a command-line interpreter or shell that provides a command line user interface for Unix-like operating systems. The shell is both an interactive command language and a scripting language, and is used by the operating system to control the execution of the system using ...
In Unix and Unix-like operating systems, job control refers to control of jobs by a shell, especially interactively, where a "job" is a shell's representation for a process group. Basic job control features are the suspending, resuming, or terminating of all processes in the job/process group; more advanced features can be performed by sending ...
Shell variables, created using the set or @ statements, are internal to C shell. They are not passed to child processes. Shell variables can be either simple strings or arrays of strings. Some of the shell variables are predefined and used to control various internal C shell options, e.g., what should happen if a wildcard fails to match anything.
A shell script is a computer program designed to be run by a Unix shell, a command-line interpreter. [1] The various dialects of shell scripts are considered to be command languages . Typical operations performed by shell scripts include file manipulation, program execution, and printing text.
A shell script (or job) can report progress of long running tasks to the interactive user. Unix/Linux systems may offer other tools support using progress indicators from scripts or as standalone-commands, such as the program "pv". [52] These are not integrated features of the shells, however.
The shell also permitted you to use shell scripts as filters, providing integrated support for handling signals, but lacked the ability to define functions. Finally, it incorporated a number of features we use today, including command substitution (using back quotes) and HERE documents to embed preserved string literals within a script."
Shell programming Mandatory Shell, the standard command language interpreter Version 7 AT&T UNIX (in earlier versions, sh was either the Thompson shell or the PWB shell) sleep: Shell programming Mandatory Suspend execution for an interval Version 4 AT&T UNIX sort: Text processing Mandatory Sort, merge, or sequence check text files Version 1 AT ...
If /bin/sh is a POSIX-compatible shell, then bar and baz are presented to the script as the positional parameter array "$@", and individually as parameters "$1" and "$2" respectively. Because the initial # is the character used to introduce comments in the POSIX shell language (and in the languages understood by many other interpreters), the ...