Chaining Linux Commands Together

Feb 03, 2009, 01:32 (0 Talkback[s])

[ Thanks to Brandon for this link. ]

"What if you wanted to run a command and when it finished, run another? Linux provides three ways to do this with a slightly different end result. The semicolon (;), ampersand (&) and the verticle pipe (|) all help the user "chain" commands together.

"[user@localhost ~]$ apt-get update ; apt-get upgrade

"In this example we are using the semicolon (;) to separate these two commands. Using a semicolon tells the shell, "once the first command finishes, run the second one". Once apt-get update finishes, the system will then run it again using the upgrade option.

"[user@localhost ~/project1]$ ./configure && make && make install

"This command is mainly used by developers, software package maintainers and Linux power users. This chain of commands compiles a program and installs it. What the double-ampersands are telling the system is "wait for the first command to successfully complete. If it does complete successfully, run the next command".

Complete Story

Related Stories:

• 10 Mistakes New Linux Administrators Make(Dec 01, 2008)
• Tip: Using find Command in Linux(Nov 19, 2008)
• Tips and Tricks for Working on the Command Line(Nov 13, 2008)
• NetCat Tutorial for Linux & Windows(Sep 22, 2008)
• Bash Shell: Take Control of PS1, PS2, PS3, PS4 and PROMPT_COMMAND(Sep 13, 2008)
• The Joys of xargs(Aug 30, 2008)
• Review: Bash Cookbook(Aug 14, 2008)
• 15 Examples To Master Linux Command Line History(Aug 13, 2008)