The Linux Newbie Guide

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Fundamentals

seq - Output Number Sequences

The seq command is a handy tool for generating number sequences in Linux. Its basic usage is as follows:
seq [OPTION]... FIRST INCREMENT LAST .

FIRST: This is the first number in the sequence.
INCREMENT: This is the step value by which the sequence will be incremented. It's optional, and if omitted, it defaults to 1.
LAST: This is the last number in the sequence.

Here is a list of some commonly used options:

-f, --format=FORMAT: Specify a custom output format using the printf-style format string. For example, -f "%02g" will generate numbers with leading zeros.
-s, --separator=STRING: Set the separator between numbers. The default separator is a newline character.
-w, --equal-width[=WIDTH]: Ensure that all numbers have the same width by padding with leading zeros if necessary. You can specify the desired width as an optional argument (e.g., seq -w 3 5).

Examples:

$ seq 1 5 ←Outputs 1 to 5 (omitting INCREMENT, defaults to 1)
1
2
3
4
5
$ seq 5 ←Outputs 1 to 5 (omitting FIRST and INCREMENT) 1
1
2
3
4
5
$ seq 1 2 5 ←Outputs 1 to 5 with FIRST=1 and INCREMENT=2
1
3
5
$ seq -f"%04g" 1 5 ←Outputs 1 to 5 with a custom format using printf
0001
0002
0003
0004
0005
$ seq -s "`echo -e "\t"`" 0 5 ←Outputs 0 to 5 with tab (\t) as a separator
0 1 2 3 4 5
$ seq -w 98 100 ←Outputs 98 to 100 with a fixed width
098
099
100
$ seq 1 3 | tac ← Counts down using the "tac" command
3
2
1

For more examples, you can refer to the provided link.