how does you find a character in a string (not a file)?

[Seren]

I feel I should know this but I"m drawing a blank:

How do you find a character in a string that's from a variable or from a command you've just run (`command`)? Is there a single shell command that does this?

[bigtomrodney]

It depends on the context. Are you looking for a specific string or just say the third character of the string for example.

To just check for a character you could use grep

grep A $(command_to_be_checked)
grep A $SOME_VARIABLE

Other wise there are a host of options for checking permissions.

[Seren]

It depends on the context. Are you looking for a specific string or just say the third character of the string for example.

To just check for a character you could use grep

grep A $(command_to_be_checked)
grep A $SOME_VARIABLE

Other wise there are a host of options for checking permissions.

Cool, thanks BTR. From its man page I couldn't tell that grep could check strings, I thought it would always interpret any string after the options and character as a filename. Btw, how is grep able to know not to look for the character in a file in the current directory by that name?

[bigtomrodney]

grep requires a file name to search, or a wildcard/globbing. So

grep something somefile.txt

Most Unix commands can read from standard input rather than a file, as Unix treats everything as a file. For a lot of commands however you need to specify a hyphen for standard input

grep something -

In the cases above the command you want to run is evaluated because of the $(somecommand) and thus this is the input for grep. This is the more modern way, in older scripts you will see the back ticks `somecommand`.

An alternative would be

somecommand |grep something

This is piping output to grep (standard input).

If you are interested check out the Advanced Bash Scripting guide at tldp.org - you can read it online or download the PDF. It's well worth the read if you will be using command line at all.

[ghostdog74]

I feel I should know this but I"m drawing a blank:

How do you find a character in a string that's from a variable or from a command you've just run (`command`)? Is there a single shell command that does this?

you can also use case

        case "$str2" in
        *${str1}*)   echo string1 in string2 ;;
        *)              echo string1 not present ;;
        esac

[Seren]

BigTom and GhostDog, thanks for your help. I'll implement one or both of these when I get the next chance.

[Seren]

It looks like my question has evolved a bit:

Is there a way test for a string within a variable, so that the test can be used in an if statement? I'm trying to have it all happen in the if statement, not by running commands and then doing RESULT_VARIABLE=$? previous to the if statement.

[teju]

hi thr....

I'm a newbie so my answer might not be so efficient..

let us say that u wanna check for the string "ss" in a variable '$line':
then one can do this:

if [ "${line##*ss*}" != "$line" ]; then
echo \'ss\' is found
else
echo \'ss\' is not found
fi

cheers

[teju]

Or if you want it to be generalized then

$str=ss
if [ "${line##*$str*}" != "$line" ]; then
echo $str is found
else
echo $str is not found
fi

[ghostdog74]

you can use case

# line="lkjsflsltestlksjflsd"
# v="test"
# case $line in *$v*) echo "found";; *) echo "not found";; esac