How to use for loop to pass a line of string from text file as separate variable for another script in Bash

Question

I am writing a bash script that accepts a manifest.txt file. It should cycle through each row of that text file and call another script to pass the text string from the row of the text file after separating the string of text by the space delimiter.

I am stuck on figuring out how to split the text string; I tried to use cut -d' ', but it has not worked for me.

Here's the example of the text file:

20200451310 B.315
30203131340 Pam 3781, no.1
20200461200 B.16
20200471180 B.116, B.198
20200471190 B.129
10107291410 B.102
30203141220 Pam 3870, no. 1
20200481160 B.525

Here's the bash script I have so far:

#!/bin/bash 
IFS=$'\n'       # make newlines the only separator
set -f          # disable globbing
for i in $(cat < "${manifest.txt}"); do
  echo " $i"
  uid = ${i | cut -d' ' -f1}
  string = ${i | cut -d' ' -f2-10}   
  echo "uid is ${uid}"
  echo "string is ${string}"
  /anotherscript.sh ${uid} ${string}
done

The result should be, for example:

/anotherscript.sh "30203141220" "Pam 3870, no. 1"

Have a look at [BashFAQ/001](https://mywiki.wooledge.org/BashFAQ/001) and [Looping through the content of a file in Bash](https://stackoverflow.com/q/1521462/3266847) to see how to read a file line by line. — Benjamin W., Dec 04 '19 at 21:33
Then, use https://www.shellcheck.net to get pointers about common mistakes (spaces around `=` in assignments etc.). — Benjamin W., Dec 04 '19 at 21:33
You're using `${ }`, but you mean `$( )` for command substitution. The command `i | cut -d' ' -f1` won't work, you have to pipe `$i` to `cut` somehow, for example with `cut -d' ' -f1 <<< "$i"`. — Benjamin W., Dec 04 '19 at 21:34
But really, instead of using `cut`, you should read each line into two variables and let Bash to the splitting for you. — Benjamin W., Dec 04 '19 at 21:35

Benjamin W. · Accepted Answer · 2019-12-04T23:43:03.930

You can simplify your script to this:

#!/usr/bin/env bash

while read -r uid string; do
    ./anotherscript.sh "$uid" "$string"
done < manifest.txt

A laundry list of mistakes in your attempt:

"${manifest.txt}" tries to perform variable expansion on manifest.txt, which isn't a variable name, leading to an error; you want manifest.txt instead
cat < somefile can be just cat somefile
In Bash, for i in $(cat somefile) can be simplified to for i in $(< somefile)

But really, you want to read lines with

read IFS= read -r i; do ...; done < manifest.txt

i | cut -d' ' -f1 doesn't make cut read $i; you have to use something like cut -d' ' -f1 <<< "$i" instead
${somecommand} is the wrong syntax; for command substitution, you want $(somecommand) instead
Assignments can't have blanks around =: uid = something should be uid=something
To split a string, read into multiple variables with read instead of using cut:
```
while read -r uid string; do ... done < manifest.txt
```
/anotherscript.sh is probably the wrong path and should be ./anotherscript.sh instead
arguments in /anotherscript.sh ${uid} ${string} should be quoted:
```
./anotherscript.sh "$uid" "$string"
```

How to use for loop to pass a line of string from text file as separate variable for another script in Bash

1 Answers1