w64devkit/man/man1/seq.1

.TH SEQ 1 2026-10-19 "w64devkit" "w64devkit Manual"
.SH NAME
seq \- print a sequence of numbers
.SH SYNOPSIS
.B seq
.RB [ \-w ]
.RB [ \-s
.IR sep ]
.RI [ first
.RI [ incr ]]
.I last
.SH DESCRIPTION
.B seq
writes the numbers from
.I first
to
.I last
in steps of
.I incr
to standard output.
With one operand, it is
.IR last .
With two, they are
.I first
and
.IR last ,
and with three,
.IR first ,
.IR incr ,
and
.IR last .
.I first
and
.I incr
default to 1.
Any other number of operands is a usage error.
.PP
Each operand is read with the C library function
.BR strtod .
It may have leading white space and a sign, and be written with a
fraction, with an exponent as in
.BR 1e3 ,
or in hexadecimal as in
.BR 0x1F .
It may also be
.BR inf ,
.BR infinity ,
or
.BR nan ,
in any case.
The decimal separator is always a period.
An empty operand is 0.
Trailing characters after the number, a value too large for a double,
and a nonzero value smaller in magnitude than about 2.2e\-308 are usage
errors.
.PP
The number at position
.IR n ,
counting from 0, is
.IR first " + " n "*" incr ,
computed as a double, so rounding errors do not accumulate.
When
.I incr
is 0 or positive,
.B seq
writes numbers as long as they are at most
.IR last .
When it is negative, it writes them as long as they are at least
.IR last .
A sequence that starts beyond
.IR last ,
such as
.BR "seq 3 1" ,
is empty: nothing is written, not even a newline, and the status is 0.
An
.I incr
of 0 repeats
.I first
forever unless
.I first
is above
.IR last .
.PP
Numbers are written in decimal, never with an exponent.
Each has as many digits after the period as there are characters after
the period in
.I first
or
.IR incr ,
whichever has more, as typed.
Every character after the period counts, so
.B 1.5e1
gives three digits, and an operand with no period, such as
.BR 1e\-1 ,
gives none.
The characters of
.I last
do not count.
Numbers are rounded to that many digits, so
.B "seq 0 1e\-1 1"
writes whole numbers only.
.PP
.B seq
writes
.I sep
between numbers, and a newline after the last number.
.SH OPTIONS
Options may be grouped, and an option's argument may be attached or be
the next argument, so
.B \-ws:
is the same as
.BR "\-w \-s :" .
.B \-\-
ends the options.
Options must come before the operands: a later word is an operand.
.PP
A word that starts with a hyphen and a digit or a period, such as
.B \-5
or
.BR \-.5 ,
is a negative number wherever it appears, and the options end before it.
A
.I sep
that looks like that must be attached to the option, as in
.BR \-s\-1 .
.TP
.B \-w
Pad the numbers with leading zeros to a common width.
The width is the largest, over all the operands including
.IR last ,
of the number of characters typed before the period, or in the whole
operand when it has none, so white space, a sign, an exponent, and a
.B 0x
prefix count.
When the numbers have digits after the period, the period and those
digits are added.
The width is computed from the text, not the values:
.B "seq \-w 0x9 0x10"
pads to four characters and writes
.BR 0009 ,
.BR 0010 ,
and so on.
Zeros go after a sign, so
.B "seq \-w \-10 5"
writes
.B \-10
through
.BR \-01 ,
then
.B 000
through
.BR 005 .
.TP
.BI "\-s " sep
Write
.I sep
between numbers instead of a newline.
It is written as is, with no backslash escapes, and may be empty.
With several
.B \-s
options, the last wins.
.TP
.B \-\-help
Print a usage message on standard output and exit with status 0.
It is recognized only as the first argument.
.SH ENVIRONMENT
.TP
.B BB_GLOBBING
Unless it is
.BR 0 ,
wildcards in the arguments are expanded, as needed when run from
.BR cmd.exe .
A busybox process started with it unset sets it to
.B 0
for its children, so commands run from the kit's shell receive their
arguments as the shell expanded them.
.TP
.BR BB_TERMINAL_MODE ", " BB_SKIP_ANSI_EMULATION
When standard output is a console, decide whether the console or busybox
interprets the escape sequences in the output, such as for color.
See
.BR busybox (1).
.TP
.B CONEMUPID
When it is set and neither of the above is, busybox uses terminal mode
0: it turns virtual terminal output off and emulates escape sequences
itself.
.TP
.BR LC_ALL ", " LC_CTYPE ", " LANG
If the first of these that is set has the value
.BR C ,
output to a console is not converted, and the console interprets the
bytes in its own code page.
.PP
Variables that affect every busybox applet are described in
.BR busybox (1).
.SH EXIT STATUS
.TP
.B 0
Success, including an empty sequence.
.TP
.B 1
Usage error: an unknown option, a missing option argument, a number of
operands other than one to three, or an operand that is not a number or
is out of range for a double.
The usage message is written to standard error, preceded for an option
error by a line such as
.BR "seq: unknown option \-\- x" .
.TP
.B 141
Standard output is a pipe whose reader has exited, found while writing
the numbers.
.TP
.B 255
Standard output could not be written when it was flushed at exit, such
as when it is closed, or when it is a pipe whose reader has exited and
the output was short enough to stay buffered until then.
No message is written.
.SH EXAMPLES
Write the numbers from 1 to 5 on one line:
.PP
.RS 4
.EX
$ seq \-s \(aq \(aq 5
1 2 3 4 5
.EE
.RE
.PP
Count down by fives, and count up from a negative number:
.PP
.RS 4
.EX
$ seq \-s \(aq \(aq 20 \-5 0
20 15 10 5 0
$ seq \-s, \-2 2
\-2,\-1,0,1,2
.EE
.RE
.PP
Write fractions; the step 0.25 sets two digits for every number:
.PP
.RS 4
.EX
$ seq 0 0.25 1
0.00
0.25
0.50
0.75
1.00
.EE
.RE
.PP
Number files with a common width:
.PP
.RS 4
.EX
$ for i in $(seq \-w 8 11); do echo img$i.png; done
img08.png
img09.png
img10.png
img11.png
.EE
.RE
.PP
Rounding makes the last number of a fractional sequence uncertain.
Here 0.3 is missing, because 3 times 0.1 is slightly more than 0.3:
.PP
.RS 4
.EX
$ seq 0 0.1 0.3
0.0
0.1
0.2
.EE
.RE
.PP
Keep 0.3 by stopping a little past it:
.PP
.RS 4
.EX
$ seq 0 0.1 0.35
.EE
.RE
.SH NOTES
Unlike GNU
.BR seq ,
this one has no format option
.RB ( \-f ),
and no long options other than
.BR \-\-help .
.PP
Numbers are doubles, so integers above 2 to the 53rd power are not all
representable.
Each number is rounded to the nearest double, so an
.I incr
that is small next to
.I first
makes numbers repeat or skip.
The count of numbers written is a 32-bit value, so a sequence of
4294967296 numbers or more starts over from
.I first
after that many, and never ends.
.PP
Standard output is binary, so the newline is a bare LF.
.PP
The C runtime expands wildcards in the arguments, even quoted ones, when
.B seq
is run from
.BR cmd.exe .
A
.I sep
such as
.B *
is then replaced by the names of the matching files, so the arguments
differ from those typed.
Set
.B BB_GLOBBING
to
.B 0
to prevent that.
.PP
Arguments may contain any Unicode character on Windows 10 version 1903
and later, and are limited to the system code page on earlier versions.
When standard output is a console, the output is converted for display
from the ANSI code page, which is UTF-8 on Windows 10 version 1903 and
later.
Escape sequences in
.IR sep ,
such as those for color, take effect, and busybox emulates them on
consoles without virtual terminal support.
.SH SEE ALSO
.BR awk (1),
.BR busybox (1),
.BR printf (1),
.BR sh (1),
.BR shuf (1)