seq

Additional Notes

seq prints a sequence of numbers, one per line, from a start value to an end value. It is handy for loops, repeated tasks, and generating numbered lists in scripts.

With one argument it counts from 1; with two it uses start and end; with three you add a step (which may be negative to count down).

Syntax

seq [options] [FIRST] LAST
seq [options] FIRST INCREMENT LAST

Parameters

• options: Flags that change output format.
• FIRST: Starting value (default 1).
• INCREMENT: Step between numbers (default 1; may be negative).
• LAST: Ending value (inclusive).

Common Options

• -s STRING, --separator=STRING: Use a custom separator instead of newline.
• -w, --equal-width: Pad with leading zeros to equal width.
• -f FORMAT, --format=FORMAT: Use a printf-style format such as %03g.
• --help: Show usage help.

Examples

seq 5

Print 1 through 5, one per line.

seq 2 2 10

Print even numbers 2, 4, 6, 8, 10.

seq 10 -1 1

Count down from 10 to 1.

seq -s, 1 5

Print 1,2,3,4,5 on one line with comma separators.

seq -w 1 10

Print 01 through 10 with equal width.

seq -f "File %03g" 1 3

Print File 001, File 002, File 003.

Practical Notes

• Use seq in for loops: for i in $(seq 1 10); do ...; done.
• Negative steps count downward; make sure FIRST is above LAST in that case.
• -w and -f make output line up nicely in reports.
• For very large ranges, consider a shell brace range like {1..10} which needs no command.