Extract a word from string in a certain position in bash script

Question

I am writing a custom pre-push hook and want to extract a certain word from a commit message in a certain position. An example commit messages structure is

GRP-0876 CHANGE CORE - (core/components/button) : Some message
GRP-0876 CHANGE SHARED - (shared/components/button) : Some message
GRP-0876 CHANGE BUS - (pages/login) : Some message

GRP-0876 - the number here can be of any length. CORE - is one of the main folders in the root. It can be one of the CORE|SHARED|CSR|ADM|BUS

I need to extract the changed root folder ( In the below example it's CORE ) and assign it to a variable. I have done a lot of research and tried out a few examples, but none worked for me.

I have tried a sed command but the output is the same commit message.

echo 'GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions' | sed -n '/CORE/'

Even though my approach is not working, I would like to make it dynamic by extracting at a specified position with the help of regex

P.S.

I am writing a bash script for the first time.

EDITED

I need to extract that value and assign to a variable

app='GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions' | sed -E 's/.* \w+ ([^[:blank:]]+) .*/\1/'
echo "$app"

This prints an empty string.

anubhava · Accepted Answer · 2023-01-09 20:03:59Z

4

Using this sed solution on the 3 lines you provided:

sed -E 's/.* (FIX|FEATURE|CHANGE|HOTFIX) ([^[:blank:]]+) .*/\2/' file

CORE
SHARED
BUS

To store this value in a variable:

app=$(echo 'GRP-0888 CHANGE SHARED - (core/components/button) : Change button dimensions' |
sed -E 's/.* (FIX|FEATURE|CHANGE|HOTFIX) ([^[:blank:]]+) .*/\2/')

Alternatively this awk should also work:

awk '$2 ~ /^(FIX|FEATURE|CHANGE|HOTFIX)$/ {print $3}' file

Where:

cat file

GRP-0876 CHANGE CORE - (core/components/button) : Some message
GRP-0876 CHANGE SHARED - (shared/components/button) : Some message
GRP-0876 CHANGE BUS - (pages/login) : Some message

edited Jan 9, 2023 at 20:03

answered Jan 9, 2023 at 18:50

anubhava

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6 Comments

Norayr Ghukasyan Over a year ago

app='GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions' | sed -E 's/.* CHANGE ([^[:blank:]]+) .*/\1/'

And then print it echo "$app" Prints an empty string.

Norayr Ghukasyan Over a year ago

Please see the updated version.

anubhava Over a year ago

You need to use:

app=$(sed -E 's/.* CHANGE ([^[:blank:]]+) .*/\1/' <<< 'GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions')

anubhava Over a year ago

Or

app=$(echo 'GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions' | sed -E 's/.* CHANGE ([^[:blank:]]+) .*/\1/')

Norayr Ghukasyan Over a year ago

Worked like a charm.Please edit your answer and include it with

app=$(echo 'GRP-0888 CHANGE SHARED - (core/components/button) : Change button dimensions' | sed -E 's/.* CHANGE ([^[:blank:]]+) .*/\1/')

.

|

j_b · Accepted Answer · 2023-01-09 19:24:06Z

1

Using a while loop:

while read -r a b c d ; do echo "$c" ; done < msgs.txt
CORE
SHARED
BUS

or capture in variable:

 app=$(while read -r a b c d ; do echo "$c" ; done <<<"GRP-0888 CHANGE CORE - (core/components/button) : Change button dimensions")
echo "$app"
CORE

answered Jan 9, 2023 at 19:24

j_b

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