-
Book Overview & Buying
-
Table Of Contents
-
Feedback & Rating
Linux Command Line and Shell Scripting Bible - Third Edition
By :
While learning about the GNU bash shell, you likely have heard the term built-in command. It is important to understand both shell built-in and non-built-in (external) commands. Built-in commands and non-built-in commands operate very differently.
An external command, sometimes called a filesystem command, is a program that exists outside of the bash shell. They are not built into the shell program. An external command program is typically located in /bin, /usr/bin, /sbin, or /usr/sbin.
The ps command is an external command. You can find its filename by using both the which and the type commands:
$ which ps
/bin/ps
$
$ type -a ps
ps is /bin/ps
$
$ ls -l /bin/ps
-rwxr-xr-x 1 root root 93232 Jan 6 18:32 /bin/ps
$
Whenever an external command is executed, a child process is created. This action is termed forking. Conveniently, the external command ps displays its current parent as well as its own forked child processes...
Change the font size
Change margin width
Change background colour