freebsd-skq/usr.bin/jot/jot.1

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.\"	@(#)jot.1	8.1 (Berkeley) 6/6/93
.\" $FreeBSD$
.\"
.Dd June 2, 2010
.Dt JOT 1
.Os
.Sh NAME
.Nm jot
.Nd print sequential or random data
.Sh SYNOPSIS
.Nm
.Op Fl cnr
.Op Fl b Ar word
.Op Fl w Ar word
.Op Fl s Ar string
.Op Fl p Ar precision
.Op Ar reps Op Ar begin Op Ar end Op Ar s
.Sh DESCRIPTION
The
.Nm
utility is used to print out increasing, decreasing, random,
or redundant data, usually numbers, one per line.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl r
Generate random data instead of the default sequential data.
.It Fl b Ar word
Just print
.Ar word
repetitively.
.It Fl w Ar word
Print
.Ar word
with the generated data appended to it.
Octal, hexadecimal, exponential,
.Tn ASCII ,
zero padded,
and right-adjusted representations
are possible by using the appropriate
.Xr printf 3
conversion specification inside
.Ar word ,
in which case the data are inserted rather than appended.
.It Fl c
This is an abbreviation for
.Fl w Ar %c .
.It Fl s Ar string
Print data separated by
.Ar string .
Normally, newlines separate data.
.It Fl n
Do not print the final newline normally appended to the output.
.It Fl p Ar precision
Print only as many digits or characters of the data
as indicated by the integer
.Ar precision .
In the absence of
.Fl p ,
the precision is the greater of the precisions of
.Ar begin
and
.Ar end .
The
.Fl p
option is overridden by whatever appears in a
.Xr printf 3
conversion following
.Fl w .
.El
.Pp
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
.Fl ""
or as an empty string.
Any three of these arguments determines the fourth.
If four are specified and the given and computed values of
.Ar reps
conflict, the lower value is used.
If fewer than three are specified, defaults are assigned
left to right, except for
.Ar s ,
which assumes a default of 1 or -1 if both
.Ar begin
and
.Ar end
are given.
.Pp
Defaults for the four arguments are, respectively,
100, 1, 100, and 1, except that when random data are requested,
the seed,
.Ar s ,
is picked randomly.
The
.Ar reps
argument is expected to be an unsigned integer,
and if given as zero is taken to be infinite.
The
.Ar begin
and
.Ar end
arguments may be given as real numbers or as characters
representing the corresponding value in
.Tn ASCII .
The last argument must be a real number.
.Pp
Random numbers are obtained through
.Xr arc4random 3
when no seed is specified,
and through
.Xr random 3
when a seed is given.
When
.Nm
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
.Fl w ,
.Fl b ,
or
.Fl p
options,
.Nm
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.
.Pp
The name
.Nm
derives in part from
.Nm iota ,
a function in APL.
.Ss Rounding and truncation
The
.Nm
utility uses double precision floating point arithmetic internally.
Before printing a number, it is converted depending on the output
format used.
.Pp
If no output format is specified or the output format is a
floating point format
.Po
.Sq E ,
.Sq G ,
.Sq e ,
.Sq f ,
or
.Sq g
.Pc ,
the value is rounded using the
.Xr printf 3
function, taking into account the requested precision.
.Pp
If the output format is an integer format
.Po
.Sq D ,
.Sq O ,
.Sq U ,
.Sq X ,
.Sq c ,
.Sq d ,
.Sq i ,
.Sq o ,
.Sq u ,
or
.Sq x
.Pc ,
the value is converted to an integer value by truncation.
.Pp
As an illustration, consider the following command:
.Bd -literal -offset indent
$ jot 6 1 10 0.5
1
2
2
2
3
4
.Ed
.Pp
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.
.Bd -literal -offset indent
$ jot -p 1 6 1 10 0.5
1.0
1.5
2.0
2.5
3.0
3.5
.Ed
.Pp
By offsetting the values slightly, the values generated by the following
command are always rounded down:
.Bd -literal -offset indent
$ jot -p 0 6 .9999999999 10 0.5
1
1
2
2
3
3
.Ed
.Pp
Another way of achieving the same result is to force truncation by
specifying an integer format:
.Bd -literal -offset indent
$ jot -w %d 6 1 10 0.5
.Ed
.Pp
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
The command
.Dl jot - 1 10
.Pp
prints the integers from 1 to 10,
while the command
.Dl jot 21 -1 1.00
.Pp
prints 21 evenly spaced numbers increasing from -1 to 1.
The
.Tn ASCII
character set is generated with
.Dl jot -c 128 0
.Pp
and the strings xaa through xaz with
.Dl jot -w xa%c 26 a
.Pp
while 20 random 8-letter strings are produced with
.Dl "jot -r -c 160 a z | rs -g 0 8"
.Pp
Infinitely many
.Em yes Ns 's
may be obtained through
.Dl jot -b yes 0
.Pp
and thirty
.Xr ed 1
substitution commands applying to lines 2, 7, 12, etc.\& is
the result of
.Dl jot -w %ds/old/new/ 30 2 - 5
.Pp
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
.Dl jot -w %d - 9.5 0 -.5
.Pp
and a file containing exactly 1024 bytes is created with
.Dl jot -b x 512 > block
.Pp
Finally, to set tabs four spaces apart starting
from column 10 and ending in column 132, use
.Dl expand -`jot -s, - 10 132 4`
.Pp
and to print all lines 80 characters or longer,
.Dl grep `jot -s \&"\&" -b \&. 80`
.Sh DIAGNOSTICS
The following diagnostic messages deserve special explanation:
.Bl -diag
.It "illegal or unsupported format '%s'"
The requested conversion format specifier for
.Xr printf 3
was not of the form
.Dl %[#][ ][{+,-}][0-9]*[.[0-9]*]?
where
.Dq ?\&
must be one of
.Dl [l]{d,i,o,u,x}
or
.Dl {c,e,f,g,D,E,G,O,U,X}
.It "range error in conversion"
A value to be printed fell outside the range of the data type
associated with the requested output format.
.It "too many conversions"
More than one conversion format specifier has been supplied,
but only one is allowed.
.El
.Sh SEE ALSO
.Xr ed 1 ,
.Xr expand 1 ,
.Xr rs 1 ,
.Xr seq 1 ,
.Xr yes 1 ,
.Xr arc4random 3 ,
.Xr printf 3 ,
.Xr random 3
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 4.2 .