How can I read each line from a file into one variable for the last field, and another variable for the other fields?

Question

How can I read a line from a file into two variables: one variable for the last field, and the the other variable for the other fields?

For example, I have a file:

hello world! 10s
It is a good day. 4m
...

I would like to read each line into two variables: one variable contains the time interval at the end of the line, and the other variable contains the fields before it. I was wondering how to do it; this is as far as I have gotten:

while read line 
do
    ...  # split $line into $message and $interval
    myprogram "$message" "$interval"
done < "$inputfile"

Thanks. The time interval will be used as argument to sleep. If sleep accepts an argument with a space within it, then yes; otherwise, no. — Tim, Nov 08 '18 at 23:04
@JeffSchaller Could you tell me how I should rewrite my while loop? I have looked at the link — Tim, Nov 08 '18 at 23:48
It's apparent that reading into variables is not your final destination; there might be other/better ways to accomplish your goal, if we knew what it was. — Jeff Schaller, Nov 08 '18 at 23:51
@JeffSchaller It is any executable myprogram which expects two arguments. — Tim, Nov 08 '18 at 23:52
Why use the shell; have myprogram read the text file directly. — Jeff Schaller, Nov 09 '18 at 00:11

score 3 · Accepted Answer · answered Nov 08 '18 at 23:06

As long as the interval contains no whitespace this should work:

#!/bin/bash

input=/path/to/input

while read -r line; do
    message=${line% *}
    interval=${line##* }
    echo "$message"
    sleep "$interval"
done < "$input"

${line% *} Will strip everything after the last space character

${line##* } Will strip everything before the last space character

How can I read each line from a file into one variable for the last field, and another variable for the other fields?

1 Answers1