Looping in Bash

Note: This guide ensures compatibility with Bash 3, which is the default on macOS and some older systems. All examples should work across Bash 3 and newer versions.

For Loop in Bash

For loops are the most commonly used loops in Bash for iterating over a series of values.

for item in list do echo "$item" done

For Loop Variations

C-style For Loop

for ((i=0; i<10; i++)) do echo "$i" done

For Loop with Range

for i in $(seq 1 5) do echo "$i" done

Note: In Bash 4+, you can use {1..5} for ranges, but seq is more compatible across versions (including v3).

One-line For Loop

for i in $(seq 1 5); do echo "$i"; done

Bash While Loop

While loops continue executing as long as a condition is true.

count=1 while [ $count -le 5 ] do echo "$count" count=$((count + 1)) done

Bash For Loop Array

Looping through arrays is a common task in Bash scripting.

fruits=("apple" "banana" "cherry") for fruit in "${fruits[@]}" do echo "$fruit" done

Bash Loop Through Files in Directory

for file in * do echo "Processing $file" done

Tip: When dealing with filenames that might contain spaces, always quote your variables: "$file"

Bash Infinite Loop

while true do echo "This will run forever" sleep 1 done

Bash Until Loop

Until loops continue executing until a condition becomes true.

count=1 until [ $count -gt 5 ] do echo "$count" count=$((count + 1)) done

Bash Loop Control

Break Statement

for i in $(seq 1 10) do if [ $i -eq 5 ] then break fi echo "$i" done

Continue Statement

for i in $(seq 1 5) do if [ $i -eq 3 ] then continue fi echo "$i" done