26.3 seq: Print numeric sequences

seq prints a sequence of numbers to standard output. Synopses:

seq [option]… last
seq [option]… first last
seq [option]… first increment last

seq prints the numbers from first to last by increment. By default, each number is printed on a separate line. When increment is not specified, it defaults to ‘1’, even when first is larger than last. first also defaults to ‘1’. So seq 1 prints ‘1’, but seq 0 and seq 10 5 produce no output. The sequence of numbers ends when the sum of the current number and increment would become greater than last, so seq 1 10 10 only produces ‘1’. increment must not be ‘0’; use the tool yes to get repeated output of a constant number. first, increment and last must not be NaN, but inf is supported. Floating-point numbers may be specified in either the current or the C locale. See Floating point numbers.

The program accepts the following options. Also see Common options. Options must precede operands.

-f format

Print all numbers using format. format must contain exactly one of the ‘printf’-style floating point conversion specifications ‘%a’, ‘%e’, ‘%f’, ‘%g’, ‘%A’, ‘%E’, ‘%F’, ‘%G’. The ‘%’ may be followed by zero or more flags taken from the set ‘-+#0 '’, then an optional width containing one or more digits, then an optional precision consisting of a ‘.’ followed by zero or more digits. format may also contain any number of ‘%%’ conversion specifications. All conversion specifications have the same meaning as with ‘printf’.

The default format is derived from first, step, and last. If these all use a fixed point decimal representation, the default format is ‘%.pf’, where p is the minimum precision that can represent the output numbers exactly. Otherwise, the default format is ‘%g’.

-s string

Separate numbers with string; default is a newline. The output always terminates with a newline.


Print all numbers with the same width, by padding with leading zeros. first, step, and last should all use a fixed point decimal representation. (To have other kinds of padding, use --format).

You can get finer-grained control over output with -f:

$ seq -f '(%9.2E)' -9e5 1.1e6 1.3e6
( 2.00E+05)
( 1.30E+06)

If you want hexadecimal integer output, you can use printf to perform the conversion:

$ printf '%x\n' $(seq 1048575 1024 1050623)

For very long lists of numbers, use xargs to avoid system limitations on the length of an argument list:

$ seq 1000000 | xargs printf '%x\n' | tail -n 3

To generate octal output, use the printf %o format instead of %x.

On most systems, seq can produce whole-number output for values up to at least 2^{53}. Larger integers are approximated. The details differ depending on your floating-point implementation. See Floating point numbers. A common case is that seq works with integers through 2^{64}, and larger integers may not be numerically correct:

$ seq 50000000000000000000 2 50000000000000000004

However, when limited to non-negative whole numbers, an increment of less than 200, and no format-specifying option, seq can print arbitrarily large numbers. Therefore seq inf can be used to generate an infinite sequence of numbers.

Be careful when using seq with outlandish values: otherwise you may see surprising results, as seq uses floating point internally. For example, on the x86 platform, where the internal representation uses a 64-bit fraction, the command:

seq 1 0.0000000000000000001 1.0000000000000000009

outputs 1.0000000000000000007 twice and skips 1.0000000000000000008.

An exit status of zero indicates success, and a nonzero value indicates failure.