How to extract text between first 2 dashes in the string using sed or grep in shell

Question

I have the string like this feature/test-111-test-test. I need to extract string till the second dash and change forward slash to dash as well.

I have to do it in Makefile using shell syntax and there for me doesn't work some regular expression which can help or this case

Finally I have to get smth like this:
input - feature/test-111-test-test
output - feature-test-111- or at least feature-test-111

feature/test-111-test-test | grep -oP '\A(?:[^-]++-??){2}' | sed -e 's/\//-/g')

But grep -oP doesn't work in my case. This regexp doesn't work as well - (.*?-.*?)-.*.

Answer 1

Another sed solution using a capture group and regex/pattern iteration (same thing Socowi used):

$ s='feature/test-111-test-test'
$ sed -E 's/\//-/;s/^(([^-]*-){3}).*$/\1/' <<< "${s}"
feature-test-111-

Where:

• -E - enable extended regex support
• s/\//-/ - replace / with -
• s/^....*$/ - match start and end of input line
• (([^-]-){3}) - capture group #1 that consists of 3 sets of anything not - followed by -
• \1 - print just the capture group #1 (this will discard everything else on the line that's not part of the capture group)

To store the result in a variable:

$ url=$(sed -E 's/\//-/;s/^(([^-]*-){3}).*$/\1/' <<< "${s}")
$ echo $url
feature-test-111-

Answer 2

You can use awk keeping in mind that in Makefile the $ char in awk command must be doubled:

url=$(shell echo 'feature/test-111-test-test' | awk -F'-' '{gsub(/\//, "-", $$1);print $$1"-"$$2"-"}')
echo "$url"
# => feature-test-111-

See the online demo. Here, -F'-' sets the field delimiter as -, gsub(/\//, "-", $1) replaces / with - in Field 1 and print $1"-"$2"-" prints the value of --separated Field 1 and 2.

Or, with a regex as a field delimiter:

url=$(shell echo 'feature/test-111-test-test' | awk -F'[-/]' '{print $$1"-"$$2"-"$$3"-"}')
echo "$url"
# => feature-test-111-

The -F'[-/]' option sets the field separator to - and /.

The '{print $1"-"$2"-"$3"-"}' part prints the first, second and third value with a separating hyphen.

See the online demo.

Answer 3

To get the nth occurrence of a character C you don't need fancy perl regexes. Instead, build a regex of the form "(anything that isn't C, then C) for n times":

grep -Eo '([^-]*-){2}' | tr / - 

Answer 4

With sed and cut

echo feature/test-111-test-test| cut -d'-' -f-2 |sed 's/\//-/'

Output

feature-test-111

---

echo feature/test-111-test-test| cut -d'-' -f-2 |sed 's/\//-/;s/$/-/'

Output

feature-test-111-

Answer 5

You can use the simple BRE regex form of not something then that something which is [^-]*- to get all characters other than - up to a -.

This works:

echo 'feature/test-111-test-test' | sed -nE 's/^([^/]*)\/([^-]*-[^-]*-).*/\1-\2/p'
feature-test-111-

Answer 6

Another idea using parameter expansions/substitutions:

s='feature/test-111-test-test'
tail="${s//\//-}"                   # replace '/' with '-'

# split first field from rest of fields ('-' delimited); do this 3x times

head="${tail%%-*}"                  # pull first field
tail="${tail#*-}"                   # drop first field

head="${head}-${tail%%-*}"          # pull first field; append to previous field
tail="${tail#*-}"                   # drop first field

head="${head}-${tail%%-*}-"         # pull first field; append to previous fields; add trailing '-'

$ echo "${head}"
feature-test-111-

Answer 7

A short sed solution, without extended regular expressions:

sed 's|\(.*\)/\([^-]*-[^-]*\).*|\1-\2|'