for loop syntax with grep in bash

Question

I want to do text processing for lines in file.txt that ends with 0, I wrote an easy form of it to ask my question clearly.

$ cat file.txt
1 343 4352 0
324 4324 4324 324
432 432 2345 0

$ cat script.sh
for i in `grep " 0$" file.txt`
do
  echo $i; 
done

I want the output to be:

1 343 4352 0

432 432 2345 0

I want $i variable to be "1 343 4352 0" and after that to be "432 432 2345 0" but in this script $i variable is valued 1 then 343

thanks , but my script isn't this. this is the easy for of it to make my question clear, I need i variable to be the out put of grep to do sth with them. and also I want to learn how to do this with for. — Fattaneh Talebi
– Fattaneh Talebi, Commented Jul 6, 2015 at 9:16

Jahid · Accepted Answer · 2015-07-06 17:55:06Z

2

You can do this:

IFS=$'\n' arr=($(grep ' 0$' file.txt))
for  i in "${arr[@]}"
do
  echo "$i"
  #do other tasks here.
done

edited Jul 6, 2015 at 17:55

answered Jul 6, 2015 at 9:18

Jahid

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1 Comment

Ed Morton Over a year ago

Fair enough, I posted an alternative then with the caveat it's also probably not what the OP really should be doing at all.

Ed Morton · Accepted Answer · 2015-07-06 18:19:13Z

2

This is almost certainly NOT the right way to do whatever it is you are trying to do but to answer the specific question you asked:

$ grep ' 0$' file |
while IFS= read -r i
do
    echo "$i"
done
1 343 4352 0
432 432 2345 0

If you are going to be doing text processing - do it in awk, not shell for simplicity, clarity, robusteness, performance, and every other desirable attribute of good software:

$ awk '/ 0$/ {i=$0; print i}' file
1 343 4352 0
432 432 2345 0

The above is just setting/using a variable to show how to do that.

edited Jul 6, 2015 at 18:19

answered Jul 6, 2015 at 18:14

Ed Morton

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Comments

foodude · Accepted Answer · 2015-07-06 11:19:05Z

0

Use the Bash built-in "REPLY"

#!/bin/bash
while read -r ;do
    echo $REPLY ;done < file.txt

cheers Karim

answered Jul 6, 2015 at 11:19

foodude

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