JOT(1)

NAME
jot - print sequential or random data

SYNOPSIS
jot [-cnr] [-b word] [-p precision] [-s string] [-w word] [reps [begin [end [s]]]]

DESCRIPTION
jot is used to print out increasing, decreasing, random, or redundant data, usually numbers, one per line.

The options are as follows:

-b word
    Just print word repetitively.

-c  This is an abbreviation for -w %c.

-n  Do not print the final newline normally appended to the output.

-p precision
    Print only as many digits or characters of the data as indicated by the integer precision. In the absence of -p, the precision is the greater of the numbers begin and end. The -p option is overridden by whatever appears in a printf(3) conversion following -w.

-r  Generate random data. By default, jot generates sequential data.

-s string
    Print data separated by string. Normally, newlines separate data.

-w word
    Print word with the generated data appended to it. Octal, hexadecimal, exponential, ASCII, zero-padded, and right-adjusted representations are possible by using the appropriate printf(3) conversion specification inside word, in which case the data is inserted rather than appended.

The last four arguments indicate, respectively, the maximum number of data, the lower bound, the upper bound, and the step size. While at least one of them must appear, any of the other three may be omitted, and will be considered as such if given as ‘-’. Any three of these arguments determines the fourth. If four are specified and the given and computed values of reps conflict, the lower value is used. If fewer than three are specified, defaults are assigned left to right, except for s, which assumes its default unless both begin and end are given.

Defaults for the four arguments are, respectively, 100, 1, 100, and 1. reps is expected to be an unsigned integer, and if given as zero is taken to be infinite. begin and end may be given as real numbers or as characters representing the corresponding value in ASCII. The last argument must be a real number.

Random numbers are obtained through arc4random(3). Historical versions of jot used s to seed the random number generator. This is no longer supported. The name jot derives in part from “iota”, a function in APL.

  Rounding and truncation
The jot utility uses double precision floating point arithmetic internally. Before printing a number, it is converted depending on the output format used.

If no output format is specified or the output format is a floating point format ( ‘f’, ‘e’, ‘g’, ‘E’, or ‘G’), the value is rounded using the printf(3) function, taking into account the requested precision.

If the output format is an integer format ( ‘c’, ‘d’, ‘o’, ‘x’, ‘u’, ‘D’, ‘O’, ‘X’, ‘U’, or ‘i’), the value is converted to an integer value by truncation.

As an illustration, consider the following command:

    $ jot 6 1 10 0.5
    1
    2
    2
    2
    3
    4

By requesting an explicit precision of 1, the values generated before rounding can be seen. The .5 values are rounded down if the integer part is even, up otherwise.

    $ jot -p 1 6 1 10 0.5
    1.0
    1.5
    2.0
    2.5
    3.0
    3.5

By offsetting the values slightly, the values generated by the following command are always rounded down:

    $ jot -p 0 6 .9999999999 10 0.5
    1
    1
    2
    2
    3
    3

Another way of achieving the same result is to force truncation by specifying an integer format:

    $ jot -w %d 6 1 10 0.5

For random sequences, the output format also influences the range and distribution of the generated numbers:

    $ jot -r 100000 1 3 | sort -n | uniq -c
    24950 1
    50038 2
    25012 3

The values at the beginning and end of the interval are generated less frequently than the other values. There are several ways to solve this problem and generate evenly distributed integers:

    $ jot -r -p 0 100000 0.5 3.5 | sort -n | uniq -c
    33374 1
    33363 2
    33263 3
    $ jot -w %d -r 100000 1 4 | sort -n | uniq -c
    33306 1
    33473 2
    33221 3

Note that with random sequences, all numbers generated will be smaller than the upper bound. The largest value generated will be a tiny bit smaller than the upper bound. For floating point formats, the value is rounded as described before being printed. For integer formats, the highest value printed will be one less than the requested upper bound, because the generated value will be truncated.

EXAMPLES
Print 21 evenly spaced numbers increasing from -1 to 1:

    $ jot 21 -1 1.00

Generate the ASCII character set:

    $ jot -c 128 0

Generate the strings xaa through xaz:

    $ jot -w xa%c 26 a

Generate 20 random 8-letter strings (note that the character ‘{’ comes after the character ‘z’ in the ASCII character set):

    $ jot -r -c 160 a { | rs -g0 0 8

Infinitely many yes(1)'s may be obtained through:

    $ jot -b yes 0

Thirty ed(1) substitution commands applying to lines 2, 7, 12, etc. is the result of:

    $ jot -w %ds/old/new/ 30 2 - 5

Create a file containing exactly 1024 bytes:

    $ jot -b x 512 > block

To set tabs four spaces apart starting from column 10 and ending in column 132, use:

    $ expand -`jot -s, - 10 132 4`

To print all lines 80 characters or longer:

    $ grep `jot -s "" -b. 80`

SEE ALSO
ed(1), expand(1), rs(1), yes(1), arc4random(3), printf(3)

HISTORY
The jot utility first appeared in 4.2BSD.

AUTHORS
John A. Kunze