CODEWITHSUNDEEP
bash
Max_IT
Max_IT

Reputation: 626

only a part of "for" loop is working

I have written a bash script, but I cannot understand what I am doing wrong. Here it is:

#!/bin/bash

VAR_LIST=('var_A' 'var_B' 'var_C')
FilePrefix='mystring_'
counter=1

for i in "${VAR_LIST[@]}"
do
        grep "$i" > "${FilePrefix}${counter}.tab.txt"
        counter=$((counter+1))
done <$1

Results: a file is created for each variable, but only the first one has data in it; the other files are empty. I have verified manually that each variable should return a few lines. The strange thing is that if I just do:

for i in "${VAR_LIST[@]}"
do 
 echo "$i"
done

I get the list of all the variables in VAR_LIST

Upvotes: 0

Views: 38

Answers (1)

Charles Duffy
Charles Duffy

Reputation: 295278

You're only opening the input file once -- which means that once the first grep has read it, there's nothing left for future ones to read.

Since bash doesn't have a way to call seek(), you'll need to re-open the file once per invocation:

for i in "${VAR_LIST[@]}"
do
        grep "$i" >"${FilePrefix}${counter}.tab.txt" <"$1"
        counter=$((counter+1))
done

Upvotes: 2

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