Erik: Reverted edits by LisaClayborn (Talk) to last version by Erik

Erik — Tue, 09 Feb 2010 16:16:29 GMT

Reverted edits by LisaClayborn (Talk) to last version by Erik

← Older revision		Revision as of 16:16, 9 February 2010
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	You can mix [[Common Commands\|commands]] to do certain things ~~like [http://www.superiorthesis.com superior thesis]~~.		You can mix [[Common Commands\|commands]] to do certain things.

	dmesg \| grep hd		dmesg \| grep hd

Merge-delete at 16:07, 9 February 2010

Merge-delete — Tue, 09 Feb 2010 16:07:06 GMT

← Older revision		Revision as of 16:07, 9 February 2010
Line 1:		Line 1:
	You can mix [[Common Commands\|commands]] to do certain things.		You can mix [[Common Commands\|commands]] to do certain things like [http://www.superiorthesis.com superior thesis].

	dmesg \| grep hd		dmesg \| grep hd

Erik: Copy from old

Erik — Sat, 06 Jun 2009 21:24:00 GMT

Copy from old

New page

You can mix [[Common Commands|commands]] to do certain things.

dmesg | grep hd

That will search dmesg and try to find the string "hd". Now piping is extremely useful. Another example of a pipe:

dmesg | less

Now this command you can see the dmesg fully and is easier to read.

You can also make longer 'pipelines' by using a pipe of several commands. For instance, to browse the last fifty lines of <code>dmesg</code>:

dmseg | tail -50 | less

<b>Redirection:</b>

This will save the dmesg information in your home directory in the file log.txt

dmesg > ~/log.txt

You can also redirect only the [[standard output|stdout]] by using '1>' or only the [[error messages|stderr]] by using '2>'.

For instance, if you want to run a command that gives a lot of junk as output, and you just want to see any errors, you can redirect the output to the null device (<code>/dev/null</code>):

mplayer /path/to/movie.avi 1> /dev/null

You can also use the > and >> to cat stdin into a new or existing file:

bash-3.1$ cat > newFile
This is a new file
you can type text here and it
get's redirected to the file newFile
ctrl-c exits

* Warning
* cat > fileThatAlreadExists WILL OVERWRITE THE FILE! be careful :-)

You can use cat to check the text you just added:

bash-3.1$ cat newFile
This is a new file
you can type text here and it
get's redirected to the file newFile
ctrl-c exits

Now that a file is created you can add to it with the >> operator

bash-3.1$cat >> newFile
This is a new line to add to newFile

And if you use cat again to read the file

bash-3.1$cat newFile
This is a new file
you can type text here and it
get's redirected to the file newFile
ctrl-c exits
This is a new line to add to newFile

[[Category:Tutorials]]

Piping - Revision history

Erik: Reverted edits by LisaClayborn (Talk) to last version by Erik

Merge-delete at 16:07, 9 February 2010

Erik: Copy from old