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In Linux, if the script was executed by a regular user, the shell would attempt to execute the command rm -rf / as a regular user, and the command would fail. However, if the script was executed by the root user, then the command would likely succeed and the filesystem would be erased. It is recommended to use sudo on a per-command basis instead.
Some Unix shells, like the POSIX standard sh shell, use an ampersand to execute a process in the background and to duplicate file descriptors. In Bash , the ampersand can separate words, control the command history, duplicate file descriptors, perform logical operations, control jobs, and participate in regular expressions .
Kernel support for interpreter directives spread to other versions of Unix, and one modern implementation can be seen in the Linux kernel source in fs/binfmt_script.c. [30] This mechanism allows scripts to be used in virtually any context normal compiled programs can be, including as full system programs, and even as interpreters of other scripts.
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.
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 shell scripts .
The test command in Unix evaluates the expression parameter. In most recent shell implementations, it is a shell builtin, even though the external version still exists.In the second form of the command, the [ ] (brackets) must be surrounded by blank spaces (this is because [is a program and POSIX compatible shells require a space between the program name and its arguments).
Editing a FreeBSD shell script for configuring ipfirewall. 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 ...
Bash, short for Bourne-Again SHell, is a shell program and command language supported by the Free Software Foundation [2] and first developed for the GNU Project [3] by Brian Fox. [4] Designed as a 100% [5] free software alternative for the Bourne shell , [6] [7] [8] it was initially released in 1989. [9]