Search results
Results From The WOW.Com Content Network
In Unix-like operating systems, true and false are commands whose only function is to always return with a predetermined exit status.Programmers and scripts often use the exit status of a command to assess success (exit status zero) or failure (non-zero) of the command.
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 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).
Compare two files; see also diff Version 1 AT&T UNIX comm: Text processing Mandatory Select or reject lines common to two files Version 4 AT&T UNIX command: Shell programming Mandatory Execute a simple command compress: Filesystem Optional (XSI) Compress data 4.3BSD cp: Filesystem Mandatory Copy files PDP-7 UNIX crontab: Misc Mandatory
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.
Previously (and in fact still) the shell did much of this job; it automatically executed itself on a text file with executable mode when the text file's name was typed as a command. Putting the facility into the system gives the following benefits. 1) It makes shell scripts more like real executable files, because they can be the subject of 'exec.'
Bash can execute the vast majority of Bourne shell scripts without modification, with the exception of Bourne shell scripts stumbling into fringe syntax behavior interpreted differently in Bash or attempting to run a system command matching a newer Bash builtin, etc. Bash command syntax includes ideas drawn from the Korn Shell (ksh) and the C ...