[SOLVED] Use of "\" (backslash) in commands

shivaa · 09-18-2012, 10:40 PM

Hello Friends,
Could anyone explain the use of "\" (backward slash) with "rm" command.
I've seen, that many people use following command when delete a file or directory:
example% \rm -rf <directory>
So why thay use fwd slash before rm?
Thanks a lot.

TobiSGD · 09-18-2012, 10:59 PM

I have never seen that. The backslash is an escape character, which is used to give characters to commands that would normally have a different meaning in the shell.
For example, if you have a filename with a space in it, for example "aaa bbb" you could not simply remove the file with

Code:

rm aaa bbb

because rm would try to remove two files, aaa and bbb, but not the file aaa bbb. To circumvent that you can either quote the filename

Code:

rm "aaa bbb"

or you escape the space in the filename

Code:

rm aaa\ bbb

EDIT: Thanks to evo2 and suicidaleggroll, I didn't know that one could escape an alias.

evo2 · 09-18-2012, 11:03 PM

Hi,

it's to avoid shell aliases and the like.

Try the following.

Code:

alias rm='rm -i'
touch foo bar
rm foo
\rm bar

when you rm foo, you should be asked to confirm (since the alias has -i), but when you \rm bar the alias is not used.

Cheers,

Evo2.

suicidaleggroll · 09-18-2012, 11:06 PM

Quote:

Originally Posted by evo2

Hi,

it's to avoid shell aliases and the like.

Try the following.

Code:

alias rm='rm -i'
touch foo bar
rm foo
\rm bar

when you rm foo, you should be asked to confirm (since the alias has -i), but when you \rm bar the alias is not used.

Cheers,

Evo2.

^ this

The leading backslash bypasses any aliases the user has set up for the command. For example, I have an alias for df, so whenever I run "df" it actually runs "df -h", just so that I don't always have to type the -h. However, if I ever want to run the df without the -h, for whatever reason, I need to run "\df" so it runs the regular version without my custom alias.

suicidaleggroll · 09-18-2012, 11:07 PM

accidental double post

shivaa · 09-19-2012, 01:04 AM

Quote:

Originally Posted by evo2

Hi,

it's to avoid shell aliases and the like.

Try the following.

Code:

alias rm='rm -i'
touch foo bar
rm foo
\rm bar

when you rm foo, you should be asked to confirm (since the alias has -i), but when you \rm bar the alias is not used.

Cheers,

Evo2.

Thanks. It's really helpful.

shivaa · 09-19-2012, 10:04 AM

Thanks a lot everyone. Answers are really helpful and cleared my doubts.