freebsd-skq/usr.bin/jot/jot.1
Sheldon Hearn 8db8a33bb9 Improve printf(3) conversion specifier parsing so that silly formats
aren't allowed and the right casts can be used for printf() statements.

Document the conversion specifier limitations and the fact that
arithmetic overflow causes a fatal error.

PR:	12611
Reported by:	Frode Vatvedt Fjeld <frodef@acm.org>
Reviewed by:	bde
1999-07-22 17:11:59 +00:00

208 lines
5.7 KiB
Groff

.\" Copyright (c) 1993
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.\" @(#)jot.1 8.1 (Berkeley) 6/6/93
.\" $Id: jot.1,v 1.5 1999/07/12 20:23:37 nik Exp $
.\"
.Dd June 6, 1993
.Dt JOT 1
.Os
.Sh NAME
.Nm jot
.Nd print sequential or random data
.Sh SYNOPSIS
.Nm jot
.Op Fl cnr
.Op Fl b Ar word
.Op Fl w Ar word
.Op Fl s Ar string
.Op Fl p Ar precision
.Op reps Op begin Op end Op s
.Sh DESCRIPTION
.Nm Jot
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 "" .
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 its default unless 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.
.Ar Reps
is expected to be an unsigned integer,
and if given as zero is taken to be infinite.
.Ar Begin
and
.Ar end
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 random 3 .
The name
.Nm
derives in part from
.Nm iota ,
a function in APL.
.Sh EXAMPLES
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 suitable choice of step size,
as in
.Dl jot - 9 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`
.Pp
.Sh SEE ALSO
.Xr ed 1 ,
.Xr expand 1 ,
.Xr rs 1 ,
.Xr yes 1 ,
.Xr printf 3 ,
.Xr random 3
.Sh BUGS
Conversion format specifiers for
.Xr printf 3
are limited to those 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}
.Pp
No bounds-checking is performed on numeric values, so arithmetic overflow
will cause a fatal error.