How to store a line number in variable (shell script,unix)? -

file.txt below :

gui : 789 gui : 789 gui : 789 gui : 789 abc : 120

the followibng gives o/p

$ grep -n "gui : 789" file.txt | cut -f1 -d:  1 2 3 4

if there n number of such gui : 789 , how store line numbers of same ?

you can use awk 1 liner:

awk '/gui : 789/{print nr}' file

to process inside loop:

while read l    echo $l done < <(awk '/gui : 789/{print nr}' file)

edit: these command work number of matches in file. store output of above line numbers in array:

arr=( $(awk '/gui : 789/{print nr}' x) )

later on process these array elements as:

echo ${arr[0]} echo ${arr[1]} ... echo ${arr[5]}

Funaction