JOT(1) FreeBSD General Commands Manual JOT(1)
NAME
jot - print sequential or random data
SYNOPSIS
jot [-cnr] [-b word] [-w word] [-s string] [-p precision]
[reps [begin [end [s]]]]
DESCRIPTION
The jot utility is used to print out increasing, decreasing, random, or
redundant data, usually numbers, one per line.
The following options are available:
-r Generate random data instead of the default sequential data.
-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.
-c This is an abbreviation for -w %c.
-s string
Print data separated by string. Normally, newlines separate
data.
-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 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 - or as an empty
string. 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 one or two are specified, defaults are assigned
starting with s, which assumes a default of 1 (or -1 if begin and end
specify a descending range). Then the default values are assigned to the
leftmost omitted arguments until three arguments are set.
Defaults for the four arguments are, respectively, 100, 1, 100, and 1,
except that when random data are requested, the seed, s, is picked
randomly. The reps argument is expected to be an unsigned integer, and
if given as zero is taken to be infinite. The begin and end arguments
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) when no seed is
specified, and through random(3) when a seed is given. When jot is asked
to generate random integers or characters with begin and end values in
the range of the random number generator function and no format is
specified with one of the -w, -b, or -p options, jot will arrange for all
the values in the range to appear in the output with an equal
probability. In all other cases be careful to ensure that the output
format's rounding or truncation will not skew the distribution of output
values in an unintended way.
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 (`E', `G', `e', `f', 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 (`D', `O', `U', `X', `c', `d',
`i', `o', `u', or `x'), 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
EXIT STATUS
The jot utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The command
jot - 1 10
prints the integers from 1 to 10, while 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 truncating
the output precision and a suitable choice of step size, as in
jot -w %d - 9.5 0 -.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`
DIAGNOSTICS
The following diagnostic messages deserve special explanation:
illegal or unsupported format '%s' The requested conversion format
specifier for printf(3) was not of the form
%[#][ ][{+,-}][0-9]*[.[0-9]*]?
where "?" must be one of
[l]{d,i,o,u,x}
or
{c,e,f,g,D,E,G,O,U,X}
range error in conversion A value to be printed fell outside the range
of the data type associated with the requested output format.
too many conversions More than one conversion format specifier has been
supplied, but only one is allowed.
SEE ALSO
ed(1), expand(1), rs(1), seq(1), yes(1), arc4random(3), printf(3),
random(3)
HISTORY
The jot utility first appeared in 4.2BSD.
AUTHORS
John A. Kunze
FreeBSD 13.1-RELEASE-p6 September 21, 2019 FreeBSD 13.1-RELEASE-p6
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