jot(1) print sequential or random data


jot [ options ] [ reps [ begin [ end [ s ] ] ] ]


Jot is used to print out increasing, decreasing, random, or redundant data, usually numbers, one per line. The options are understood as follows.
Generate random data instead of sequential data, the default.
-b word
Just print word repetitively.
-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 are inserted rather than appended.
This is an abbreviation for -w %c.
-s string
Print data separated by string. Normally, newlines separate data.
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 precisions of begin and end. The -p option is overridden by whatever appears in a printf(3) conversion following -w.

The last four arguments indicate, respectively, the number of data, the lower bound, the upper bound, and the step size or, for random data, the seed. 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, except that when random data are requested, s defaults to a seed depending upon the time of day. 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 random(3). The name jot derives in part from iota, a function in APL.


The command

jot 21 -1 1.00

prints 21 evenly spaced numbers increasing from -1 to 1. The ASCII character set is generated with

jot -c 128 0

and the strings xaa through xaz with

jot -w xa%c 26 a

while 20 random 8-letter strings are produced with

jot -r -c 160 a z | rs -g 0 8

Infinitely many yes's may be obtained through

jot -b yes 0

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

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

The stuttering sequence 9, 9, 8, 8, 7, etc. can be produced by suitable choice of precision and step size, as in

jot 0 9 - -.5

and a file containing exactly 1024 bytes is created with

jot -b x 512 > block

Finally, to set tabs four spaces apart starting from column 10 and ending in column 132, use

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

and to print all lines 80 characters or longer,

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