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A page for each applet in the kit, plus .so stubs for aliases such as egrep and unxz. Each was written from the pinned busybox-w32 source with the kit's patches and configuration, then checked against the source and by experiment. The NOTES sections cover Windows behavior. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
132 lines
3.0 KiB
Groff
132 lines
3.0 KiB
Groff
.TH NPROC 1 2026-10-19 "w64devkit" "w64devkit Manual"
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.SH NAME
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nproc \- print the number of processors available
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.SH SYNOPSIS
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.B nproc
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.RB [ \-\-all ]
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.RB [ \-\-ignore=\c
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.IR N ]
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.SH DESCRIPTION
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.B nproc
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prints the number of logical processors available to it, as a decimal
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number on a line of its own on standard output.
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The number is never less than 1.
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Operands are ignored.
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.PP
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The count is the number of bits set in the process affinity mask, which
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is the set of processors the process may run on.
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An unrestricted mask holds every processor in the system, within the
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limits given in NOTES.
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A process inherits its mask from its parent, so it can be restricted, for
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example by
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.B start /affinity
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in
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.BR cmd.exe .
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Only the affinity mask is consulted.
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.SH OPTIONS
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There are no short options.
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Long options may be abbreviated to any unique prefix, so
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.B \-\-al
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means
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.BR \-\-all ,
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and
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.B \-\-ig=1
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means
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.BR \-\-ignore=1 .
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Options may follow operands, unless
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.B POSIXLY_CORRECT
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is set.
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.B \-\-
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ends the options.
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.TP
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.B \-\-all
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Count the processors in the system instead of those available to the
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process.
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This uses the system affinity mask in place of the process mask, so a
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restricted process still counts every processor.
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.B \-\-ignore
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still applies.
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.TP
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.BI \-\-ignore= N
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Subtract
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.I N
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from the count, but never go below 1.
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.I N
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is a nonnegative decimal integer no greater than 2147483647.
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The argument may also be the next command line argument.
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If the option is repeated, the last one applies.
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.TP
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.B \-\-help
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When it is the first argument, print a usage message on standard output
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and exit with status 0, ignoring the other arguments.
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In any other position it is an unknown option.
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.SH ENVIRONMENT
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.TP
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.B POSIXLY_CORRECT
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Read by the C library's option parser.
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When set, option parsing stops at the first operand, so options after it
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are treated as operands and ignored.
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.SH EXIT STATUS
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.TP
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.B 0
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Success.
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.TP
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.B 1
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An unknown option, a missing or invalid argument to
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.BR \-\-ignore ,
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or an argument given to
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.BR \-\-all .
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A message is written to standard error, followed by a usage message
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unless the cause is an invalid
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.B \-\-ignore
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number.
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.SH EXAMPLES
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Run
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.B make
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with one job per processor:
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.PP
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.RS 4
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.EX
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$ make \-j"$(nproc)"
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.EE
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.RE
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.PP
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Leave one processor free for other work:
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.PP
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.RS 4
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.EX
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$ make \-j"$(nproc \-\-ignore=1)"
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.EE
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.RE
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.PP
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Count the processors of a process restricted to the first two:
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.PP
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.RS 4
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.EX
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$ cmd /c start /affinity 3 /b /wait nproc
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2
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.EE
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.RE
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.SH NOTES
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Differences from GNU
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.BR nproc :
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there is no
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.BR \-\-version ,
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the
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.B OMP_NUM_THREADS
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and
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.B OMP_THREAD_LIMIT
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variables are not read, and extra operands are ignored rather than
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rejected.
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.PP
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The affinity mask is one machine word and covers one processor group, so
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a 64-bit build counts at most 64 processors, and a 32-bit build at most
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32.
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On a system with more than 64 processors, Windows reports the mask of a
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single processor group, or an empty mask when the process has threads in
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several groups.
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If the mask is empty or cannot be read, the count is 1.
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.SH SEE ALSO
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.BR busybox (1),
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.BR make (1)
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