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I have a string like /feature/abc-1245_branch_name, I wanted to extract abc-1245 from the string and store it into a different variable.

I tried using sed but didn't worked out well.

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  • Will an underscore always follow the string you need extracted? Will there ever be more than one directory before it? – jesse_b Apr 22 at 16:48
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    Is the existing string also in a variable? What defines the boundaries of your result? "After the second forward slash until the first underscore"? Something else? – Jeff Schaller Apr 22 at 16:50
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    For future questions, don't just say "it didn't work". Rather, show what you tried, and explain what unexpected result you got. – berndbausch Apr 23 at 1:46
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    What is the rule? – pLumo Apr 23 at 6:07
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string=/feature/abc-1245_branch_name

different_variable=${string%%_*}
different_variable=${different_variable##*/}

printf '%s\n' "$different_variable"

This uses standard parameter substitutions to first remove the bit after the first underscore, and then the bit before the last slash.

  • ${variable%%pattern} removes the longest substring matching pattern from the end of $variable.
  • ${variable##pattern} removes the longest substring matching pattern from the start of $variable.

If you know what _branch_name actually is,

string=/feature/abc-1245_branch_name

different_variable=$( basename "$string" '_branch_name' )

printf '%s\n' "$different_variable"

This treats the string as a pathname (even though it may not be an actual pathname), and uses basename to get the last path component (i.e. "the filename"). The basename utility is also able to remove a filename suffix, so we use that to remove the known string _branch_name.

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Using awk (depending on how little variation your input string can have):

awk -F[_/] '{print $3}' <<<"$string"

If you want to be able to handle more complex directory structures you could use basename first

basename "$string" | awk -F_ '{print $1}'

To store in a variable use command substitution

variable=$(awk -F[_/] '{print $3}' <<<"$string")
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And since no answer yet is based on sed and you asked for it;

$ string="/feature/abc-1245_branch_name"
$ sed -e 's/^.*\///; s/_.*$//' <<<"$string"
abc-1245

Use command substitution as @jesse_b suggests to put the result into a variable:

$ result=$(sed -e 's/^.*\///; s/_.*$//' <<<"$string")
$ echo $result
abc-1245

However, unless your string becomes a lot more complex to parse and parsing/filtering patterns change from string to string, i would use @kusalananda's pure Bash solution. It does the exact same thing as I do here with sed, i.e. greedy pattern matching, but in this simple case, pure Bash is probably the "natural" choice.

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