Using wildcard in bash-variable for echo and grep

Question

I am trying to come up with a function that searches a given file for a given pattern. If the pattern is not found it shall be appended to the file.

This works fine for some cases, but when my pattern includes special characters, like wildcards (*) this method fails.

Patterns that work:
pattern="some normal string"

Patterns that don't work:
pattern='#include "/path/to/dir/\*.conf"'

This is my function:

check_pattern() {
    if ! grep -q "$1" $2
    then
        echo $1 >> $2
    fi
}

I' calling my function like this:
check_pattern $pattern $target_file

When escaping the wildcard in my pattern variable to get grep running correctly echo interprets the \ as character.

So when I run my script a second time my grep does not find the pattern and appends it again.

To put it simple: Stuff that gets appended:
#include "/path/to/dir/\*.conf"

Stuff that i want to have appended:
#include "/path/to/dir/*.conf"

Is there some way to get my expected result without storing my echo-pattern in a second variable?

Please edit your question to show us how you use your function `check_pattern`. — oliv, Sep 24 '19 at 12:25
added the part above, calling the function like this: `check_pattern $pattern $target_file` — S.Mathes, Sep 24 '19 at 13:13
There are a few options on grep that might do much of what you want already: `-F` fixed strings will ignore any regex symbols `-c` count - says how many matches were found - you are interested in an answer of 0 `-m` max num matches per file - same idea, buit aborts early `-H` print filename even if there is only 1 file. — Gem Taylor, Sep 24 '19 at 16:15

score 1 · Answer 1 · edited Dec 02 '19 at 11:01

1

Use

grep -f

and

check_pattern "$pattern" "$target_file"

edited Dec 02 '19 at 11:01

tripleee

175,061
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answered Dec 02 '19 at 10:20

Flo

11
2

score 0 · Accepted Answer · answered Sep 25 '19 at 07:04

0

Thanks all, I got it now.

Using grep -F as pointed out by Gem Taylor in combination with calling my function like this check_pattern "$pattern" "$target_file" did the tricks.

answered Sep 25 '19 at 07:04

S.Mathes

21
3

Using wildcard in bash-variable for echo and grep

2 Answers2