Command substitution
Facility that allows a command to be run and its output to be pasted back on the command line as arguments to another command.
- Command substitution9 related topics
Bourne shell
Shell command-line interpreter for computer operating systems.
Command substitution using backquotes:.
C shell
Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s.
Like all Unix shells, it supports filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing and iteration.
Pipeline (Unix)
Mechanism for inter-process communication using message passing.
To remedy this issue, the "pipemill" can instead be fed from a here document containing a command substitution, which waits for the pipeline to finish running before milling through the contents.
Unix shell
Command-line interpreter or shell that provides a command line user interface for Unix-like operating systems.
All Unix shells provide filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing and iteration.
Bash (Unix shell)
Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell.
Like most Unix shells, it supports filename globbing (wildcard matching), piping, here documents, command substitution, variables, and control structures for condition-testing and iteration.
Here document
File literal or input stream literal: it is a section of a source code file that is treated as if it were a separate file.
Some shells treat them as a format string literal, allowing variable substitution and command substitution inside the literal.
Metacharacter
Character that has a special meaning to a computer program, such as a shell interpreter or a regular expression engine.
In some Unix shells and MS-DOS/Windows Command Prompt, the less-than sign and greater-than sign ("<" and ">") are used for redirection and the backtick/grave accent ("`") is used for command substitution.
Backtick
Typographical mark used mainly in computing.
Many of the Unix shells and the programming languages Perl, PHP, and Ruby use pairs of this character to indicate command substitution, that is, substitution of the standard output from one command into a line of text defining another command.
Make (software)
Build automation tool that automatically builds executable programs and libraries from source code by reading files called Makefiles which specify how to derive the target program.
Macros can be composed of shell commands by using the command substitution operator, denoted by backticks (`).