print sequential or random
jot is used to print out increasing,
decreasing, random, or redundant data, usually numbers, one per line.
The options are as follows:
- Just print word repetitively. Overrides earlier
- This is an abbreviation for
%c. Overrides earlier
- Do not print the final newline normally appended to the output.
- 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
-poption is overridden by whatever appears in a printf(3) conversion following
- Generate random data. By default,
jotgenerates sequential data.
- Print data separated by string. Normally, newlines separate data.
- 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. Overrides earlier
The last four arguments specify the length of the output sequence, its start and end points, and the step size. Any three of these arguments determine the fourth. If the given and computed values for reps conflict, the lower value is used.
Arguments can be omitted by specifying a
-’. The default values for
end, and step are 100, 1, 100,
and 1, respectively. Omitted values are computed if possible or assume the
default. A special case arises if only begin and
end are specified: if begin is
greater than end then step is
set to −1, otherwise it is set to 1; afterwards
reps is computed.
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
used step 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
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
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:
$ jot -r -c 160 a z | 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`
ed(1), expand(1), rs(1), yes(1), arc4random(3), printf(3)
jot utility first appeared in
John A. Kunze