check if a variable contains a string

melanie_pfefer · #1 (**permalink**) 12-11-2008

hi

I have an if condition that states:

if [$x does not contain $y]; then
exit

how to translate this?

$x is a path
$y is a string that comes at the end of the path

thx

jim mcnamara · #2 (**permalink**) 12-11-2008

one way

Code:

echo "$x" | grep -q "$y" 
if [[ $? -ne 0 ]] ; then
   exit
fi

bakunin · #3 (**permalink**) 12-11-2008

If "$y" always comes at the end of "$x" and (you said the content is a path) is preceeded by a slash ("/") you could use the shells variable expansion feature to trim "$x" accordingly and compare if it equals to "$y". "${x##*/}" suppresses every content of "$x" up to the last slash:

Code:

x="/a/b/c/d/e"
y="f"                   # comment this, uncomment the following line and run again
# y="e"                 

if [ "${x##*/}" = "$y" ] ; then
     echo "x and y are equal"
else
     echo "x and y are different"
fi

Note that "equal" means just "equal in the mentioned regard".

i hope this helps.

bakunin

melanie_pfefer · #4 (**permalink**) 01-10-2009

hi

the script works fine if x="/a/b/c/d/e"

but the script does not work if x="/a/b/c/d/e/"?

i mean the last slash is after the last string.

any idea?

thanks

jim mcnamara · #5 (**permalink**) 01-11-2009

If you use bash 3.0 or greater try

Code:

if [[ $var =~ "*/$" ]] ; then
   var=$( dirname $var)
fi

else try

Code:

echo "$var" | grep -q '*/$'
if [[ $? -eq 0 ] ; then
   var=$(dirname $var)
fi

melanie_pfefer · #6 (**permalink**) 01-12-2009

is there a better solution that gets the last string and removes the trailing slash if it exists?

thanks.

joeyg · #7 (**permalink**) 01-12-2009

Code:

> echo $sample
/a/b/c/d/e
> echo $sample1
/a/b/c/d/e/

> echo $sample | sed "s/\/$//" | awk -F"/" '{print $NF}'
e
> echo $sample1 | sed "s/\/$//" | awk -F"/" '{print $NF}'
e

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