til/unix/generate-a-sequence-of-numbered-items.md

Generate A Sequence Of Numbered Items

The seq command will output the specified sequence of numbers.

❯ seq 1 5
1
2
3
4
5

With the -f (--format) flag we can interpolate those numbers as part of a string.

❯ seq -f "day_%02g" 1 5
day_01
day_02
day_03
day_04
day_05

The %g indicates that there is a format specifier for a numeric type which is where seq will inject the current value in the sequence. The 02 indicates that it should be 0 padded to 2 digits.

We can then pipe this to another unix command, such as mkdir in order to quickly create a bunch of directories for, say, Advent of Code.

❯ mkdir aoc_2024
❯ cd aoc_2024
❯ seq -f "day_%02g" 1 25 | xargs mkdir

See man seq for more details.