Awk how to find a match of variable with paranthesis?

July 28, 2022

I have a file some_file.txt , in which I want to find a match line by name inside square brackets (it must bee exact match as some words may be repeated – like foo in example below).
The document contents looks like this:

[foo](url)
[foo Foo](url)
[bar (Bar)](url)
[fizz buzz](url)

I came up with the following, but it breaks when you specify name with paranthesis.

file="some_file.txt"

name="foo" # Good
name="foo Foo" # Good
name="bar (Bar)" # No match :(
name="fizz buzz" # Good

matched_line=$(awk -v n="${name}]" '$0 ~ n {print NR}' "${file}")

I tried to escape paranthesis like so name="bar \(Bar\)", but it doesn’t help.

>Solution :

Use a non-regex search using index function:

awk -v n='bar (Bar)' 'index($0, n) {print NR}' file
3

# be more precise and search with surrounding [ .. ]
awk -v n='bar (Bar)' 'index($0, "[" n "]") {print NR}' file
3

index function preforms plain text search in awk hence it doesn’t require any escaping of special characters.

Using all search terms:

for name in 'foo' 'foo Foo' 'bar (Bar)' 'fizz buzz'; do
   awk -v n="$name" 'index($0, "[" n "]") {print NR, n}' file
done

1 foo
2 foo Foo
3 bar (Bar)
4 fizz buzz