what does a "\" specify

Message

funboy.ch · Post by **funboy.ch** » Thu May 25, 2006 7:53 am

Hi folks, new to linux and was wondering what the "\" does in the command below. I'm installing fluxbox on gentoo btw.

# emerge commonbox-styles commonbox-styles-extra \
fluxbox-styles-fluxmod gentoo-artwork

Cheers

Earthwings · Post by **Earthwings** » Thu May 25, 2006 8:07 am

It indicates that the line should not end there, i.e. the two lines should be interpreted as one line. So

Code: Select all

emerge foo bar

and

Code: Select all

emerge foo \
bar

are the same.

To complete it, the # indicates you have to execute it in a shell logged in as root, while $ normally is used for commands that should be run as normal user.

funboy.ch · Post by **funboy.ch** » Thu May 25, 2006 8:13 am

cheers mate, i'm already starting to like linux.

While I'm at it, what do the && do in the line below?

emerge --sync && emerge -u fluxbox

Thanks again, greatly appreciated

troymc · Post by **troymc** » Thu May 25, 2006 8:30 am

The \ is a line continuation symbol.

When \
I type \
something like this.

The shell sees one long line: "When I type something like this."

It's so you can break up long lines into multiple short lines.

&& is a logical AND. When used on the command line like you showed, its effect is to only running the 2nd command if the 1st command completes successfully.

So with that command line, emerge -u fluxbox will only be run if the emerge --sync completes successfully.

FYI, the complement of && is ||. A logical OR. It's effect is to only run the 2nd command when the 1st command fails. So you will often see it used like this:

emerge --sync || echo "ERROR: emerge --sync FAILED!"

troymc

funboy.ch · Post by **funboy.ch** » Thu May 25, 2006 9:06 am

Wow, thanks alot m8. Really appreciate it.

PsychoticRetina · Post by **PsychoticRetina** » Thu May 25, 2006 9:07 am

command 1 && command2 means: run command 1, then run command 2. command 2 will only be run if command 1 finishes succesfully.

command 1 ; command 2 means same as the previous, except command 2 will be executed regardless of whether command 1 is executed succesfully.

asiobob · Post by **asiobob** » Fri May 26, 2006 9:56 am

you might also want to read here for introduction to shells by examples
http://www.gentoo.org/doc/en/articles/b ... ple-p1.xml

its for the bash shell which you are probably using

funboy.ch · Post by **funboy.ch** » Fri May 26, 2006 11:02 am

cheers mate