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Bash — parallel command execution

There are three ways to execute commands in parallel using bash

• plain bash: no external dependencies to be installed
• parallel: a very smart tool to execute commands in parallel
• xargs: a swiss knife tool that every Linux user must know

plain bash

Save the following as configuration.cfg

/var,*.log,log_res.txt
/var,*.gz,gzip_res.txt

Save the following as bash_plain_parallel.sh

#!/bin/bash
for n in $(cat ./configuration.cfg)
do
 DIRECTORY=$(echo $n | cut -d "," -f 1)
 FILES=$(echo $n | cut -d "," -f 2)
 RESULTS=$(echo $n | cut -d "," -f 3)
 CMD="find "${DIRECTORY}" -name "${FILES}" > "${RESULTS}
 eval ${CMD} &
done
wait
echo "Script execution completed"

make the file executable

$ chmod +x bash_plain_parallel.sh

Explaining the script

The script reads each file of configuration.cfg, each line is stored in $n variable

for n in $(cat ./configuration.cfg)

Then each $n configuration line is spitted with “,” as delimiter

DIRECTORY=$(echo $n | cut -d "," -f 1)
FILES=$(echo $n | cut -d "," -f 2)
RESULTS=$(echo $n | cut -d "," -f 3)