Bash 5 reference · Shell Builtins and Syntax

while (Bash builtin)

Repeat commands while a condition succeeds; with read, it's the standard way to process input line by line.

Bash 5

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Syntax

while COMMANDS; do ...; done

Parameter	Description
`break / continue`	Leave the loop / skip to the next iteration.
`until`	Loop while the condition fails.

A counter loop

n=0
while (( n < 3 )); do (( n++ )); echo "try $n"; done

Output

try 1
try 2
try 3

Run this on your computer — see “Get Started” for setup.

Process lines, skipping empty ones

printf 'a\n\nb\n' | while IFS= read -r line; do [[ -z $line ]] && continue; echo "got $line"; done

Output

got a
got b

Run this on your computer — see “Get Started” for setup.

for · Loop over words, files, ranges or array elements, or use the C-style form for counters.
read · Read a line from standard input into variables, splitting on IFS; use -r to keep backslashes and -p for a prompt.
Bash Loops · tutorial