AND OR operator

vicky007aggrwal · 08-22-2013, 01:42 AM

I would like to use multiple commands in below command

[ $? == 0 ] && echo "directory exits" || echo "no Directory";mkdir -p /amt

But using multiple commands in && and || is somehow not working as expected
Can somebody pls help me in understand the syntactical issue in above command.

If there is any web link available for this, that will be great help

Thanks in advance

astrogeek · 08-22-2013, 01:53 AM

It is probably working as you told it to, but you did not tell it correctly...

You do not say how it is failing so I will guess and say that it always attempts to create the directory...

Code:

[ $? == 0 ] && echo "directory exits" || echo "no Directory";mkdir -p /amt

If you intend for the OR clause to echo then make the directory, that is not what you are telling it. The trailing ';' ends the logical && ... || statement and the mkdir always executes.

What you need is...

Code:

[ $? == 0 ] && echo "directory exits" || echo "no Directory" && $(mkdir -p /amt)

If that is not what you need, please tell us how it is not working for you.

pan64 · 08-22-2013, 02:47 AM

just group them:

Code:

like this
[[ <some test> ]] && ( <true case> ) || ( <false case> )

in your case:
[[ $? -eq 0 ]] && echo "directory exits" || ( echo "no Directory";mkdir -p /amt )

use -eq to integer comparison

Firerat · 08-22-2013, 03:48 AM

and since $? is just the exit code of last command

Code:

[[ $(SomeComand) ]] && echo "directory exits" || ( echo "no Directory";mkdir -p /amt )

BUT, guessing based on context

Code:

[[ -d "/path/to/someDir" ]] && echo "directory exits" || ( echo "no Directory";mkdir -p /amt )

could also use test -d "/path/to/someDir"

http://www.tldp.org/LDP/Bash-Beginners-Guide/html/
http://www.tldp.org/LDP/abs/html/

pan64 · 08-22-2013, 04:04 AM

in that case a simple mkdir -p <dir> is sufficient, it will make that check

Firerat · 08-22-2013, 04:39 AM

true, but quietly

mkdir -vp

will tell you when it makes one, and say nothing otherwise

Code:

mkdir -vp amt;echo $?
mkdir: created directory ‘amt’
0
mkdir -vp amt;echo $?
0