optimizing-bash

how to optimize bash script

tags: learning programming

content

• bash itself isn’t slow, it’s how you use it
  • Bash is not slow at running commands. It’s slow at being a programming language.

avoid huge loops

• below code spawns an unknown number of processes
  • if there’re 1000 files, 1000 processes will be spawned

for file in *; do 
	wc -l "$file"
done 

• do this intead:

wc -l *

use other process for heavy lifting

• Use awk, sed, grep, find for heavy operations.

command usage

• Certain command usages can be streamlined to enhance performance. For example, instead of piping echo to another command, use direct file writes or built-in print options:

# Less efficient
echo "Some text" | grep "text”
 
# More efficient
grep "text" <<< "Some text"

• Avoid Using cat for Repeated I/O Work

# Less efficient
cat largefile.txt | while read line; do
    echo "Processing $line"
done
 
# More efficient
while read line; do
    echo "Processing $line"
done < largefile.txt

up

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reference

• Basic Script Optimization Techniques - Linux Bash
• BashGuide/Practices - Greg’s Wiki