||FreeBSD General Commands Manual
print sequential or random data
jot utility is used to print out increasing,
decreasing, random, or redundant data, usually numbers, one per line.
The following options are available:
- Generate random data instead of the default sequential data.
- Just print word repetitively.
- 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
conversion specification inside word, in which case
the data are inserted rather than appended.
- This is an abbreviation for
- Print data separated by string. Normally, newlines
- 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 precisions
of begin and end. The
-p option is overridden by whatever appears in a
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
when no seed is specified, and through
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
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.
jot derives in part from
iota, a function in APL.
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
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
As an illustration, consider the following command:
$ jot 6 1 10 0.5
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
By offsetting the values slightly, the values generated by the
following command are always rounded down:
$ jot -p 0 6 .9999999999 10 0.5
Another way of achieving the same result is to force truncation by
specifying an integer format:
jot utility exits 0 on success,
and >0 if an error occurs.
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
Infinitely many yes's may be obtained
jot -b yes 0
substitution commands applying to lines 2, 7, 12, etc. is the result of
jot -w %ds/old/new/ 30 2 -
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
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
and to print all lines 80 characters or longer,
The following diagnostic messages deserve special explanation:
grep `jot -s "" -b .
- illegal or unsupported format '%s'
- The requested conversion format specifier for
was not of the form
where “?” must be one of
- 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
jot utility first appeared in
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