How to check if a file contains a specific string using Bash
bash, grep, shell
Solution
if grep -q SomeString "$File"; then
Some Actions # SomeString was found
fi
You don't need `[[ ]]` here. Just run the command directly. Add `-q` option when you don't need the string displayed when it was found.
The `grep` command returns 0 or 1 in the exit code depending on the result of search. 0 if something was found; 1 otherwise.
$ echo hello | grep hi ; echo $?
1
$ echo hello | grep he ; echo $?
hello
0
$ echo hello | grep -q he ; echo $?
0
You can specify commands as an condition of `if`. If the command returns 0 in its exitcode that means that the condition is true; otherwise false.
$ if /bin/true; then echo that is true; fi
that is true
$ if /bin/false; then echo that is true; fi
$
As you can see you run here the programs directly. No additional `[]` or `[[]]`.
Problem
I want to check if a file contains a specific string or not in bash. I used this script, but it doesn't work: ``` if [[ 'grep 'SomeString' $File' ]];then # Some Actions fi ``` What's wrong in my code?