CODEWITHSUNDEEP
bashparallel-processingpipeoutput
dhokas
dhokas

Reputation: 1789

execute a list of commands and store outputs into a list

I'm receiving as input a stream of commands:

command1
command2
command3

From this, I would like to create a file output.txt containing:

command1 output1
command2 output2
command3 output3

Where the output_i is the output of command_i (each command returns a single integer). I can do that using parallel and paste successively, but I was wondering whether there is a way to get output.txt in a single bash call.

EDIT with parallel, this is how I do it:

cat commands.txt | parallel -k > outputs_only.txt
paste commands.txt outputs_only.txt > outputs.txt

Upvotes: 1

Views: 49

Answers (1)

Inian
Inian

Reputation: 85550

Just a loop in bash with input-redirection on the file containing the commands,

#!/bin/bash

while read -r line; do 
    echo "$line" "$(eval "$line")"
done < commands.txt > output.txt

Or in a single-line as

while read -r line; do echo "$line" "$(eval "$line")"; done < commands.txt > output.txt

In case you want to read from stdin and not from a file, just pipe the stream to the loop,

< command-producing-stream > | while read -r line; do echo "$line" "$(eval "$line")"; done > output.txt

Upvotes: 2

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