135 lines
3.1 KiB
Plaintext
135 lines
3.1 KiB
Plaintext
'\" t
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.\" @(#)sysconf.2v 1.1 94/10/31 SMI; new for 4.1, POSIX
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.TH SYSCONF 2V "21 January 1990"
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.SH NAME
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sysconf \- query system related limits, values, options
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.SH SYNOPSIS
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.LP
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.nf
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.ft B
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#include <unistd.h>
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.ft
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.fi
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.LP
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.nf
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.ft B
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long sysconf(name)
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int name;
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.ft R
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.fi
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.SH DESCRIPTION
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.IX "sysconf()" "" "\fLsysconf()\fP \(em get configurable system variables" ""
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.IX configure "system variables"
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.IX variables "get configurable system variables"
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.LP
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The
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.B sysconf(\|)
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function provides a method for the
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application to determine the current value of a configurable system
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limit or option (variable).
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The value does not change during the
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lifetime of the calling process.
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.\".LP
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.\"Don's blurb about setrlimit()?
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.LP
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The convention used throughout sections 2 and 3 is that
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.SM {LIMIT}
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means that
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.SM LIMIT
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is something that
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can change from system to system and applications that
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want accurate values need to call
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.BR sysconf(\|) .
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These values are things that have been historically available in
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header files such as
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.BR <sys/param.h> .
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.LP
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The following lists the conceptual name and meaning of each
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variable.
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.LP
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.\" === troff version ===
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.if n .ig IG
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.RS
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.TS
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lI lI
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l l .
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Name Meaning
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_
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\s-1{ARG_MAX}\s0 Max combined size of \fBargv[\|]\fP & \fBenvp[\|]\fR.
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\s-1{CHILD_MAX}\s0 Max processes allowed to any \s-1UID\s0.
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\s-1{CLK_TCK}\s0 Ticks per second (\fBclock_t\fR).
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\s-1{NGROUPS_MAX}\s0 Max simultaneous groups one may belong to.
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\s-1{OPEN_MAX}\s0 Max open files per process.
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\s-1{_POSIX_JOB_CONTROL}\s0 Job control supported (boolean).
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\s-1{_POSIX_SAVED_IDS}\s0 Saved ids (\fBseteuid(\|)\fR) supported (boolean).
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\s-1{_POSIX_VERSION}\s0 Version of the \s-1POSIX.1\s0 standard supported.
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.TE
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.RE
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.IG
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.\" === end troff version ===
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.\" === nroff version ===
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.if t .ig IG
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.RS
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.TS
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lI lI
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l l .
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Name Meaning
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\s-1{ARG_MAX}\s0 Max combined size of \fBargv[\|]\fP & \fBenvp[\|]\fR.
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\s-1{CHILD_MAX}\s0 Max processes allowed to any \s-1UID\s0.
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\s-1{CLK_TCK}\s0 Ticks per second (\fBclock_t\fR).
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\s-1{NGROUPS_MAX}\s0 Max simultaneous groups one may
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belong to.
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\s-1{OPEN_MAX}\s0 Max open files per process.
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\s-1{_POSIX_JOB_CONTROL}\s0 Job control supported (boolean).
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\s-1{_POSIX_SAVED_IDS}\s0 Saved ids (\fBseteuid(\|)\fR) supported
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(boolean).
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\s-1{_POSIX_VERSION}\s0 Version of the \s-1POSIX.1\s0 standard
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supported.
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.TE
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.RE
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.IG
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.\" === end nroff version ===
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.LP
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The following table lists the conceptual name of each variable
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and the flag passed to
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.B sysconf(\|)
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to retrieve the value of each variable.
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.LP
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.RS
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.TS
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lI lI
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l lB .
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Name Sysconf flag
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_
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\s-1{ARG_MAX}\s0 \s-1_SC_ARG_MAX\s0
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\s-1{CHILD_MAX}\s0 \s-1_SC_CHILD_MAX\s0
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\s-1{CLK_TCK}\s0 \s-1_SC_CLK_TCK\s0
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\s-1{NGROUPS_MAX}\s0 \s-1_SC_NGROUPS_MAX\s0
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\s-1{OPEN_MAX}\s0 \s-1_SC_OPEN_MAX\s0
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\s-1{_POSIX_JOB_CONTROL}\s0 \s-1_SC_JOB_CONTROL\s0
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\s-1{_POSIX_SAVED_IDS}\s0 \s-1_SC_SAVED_IDS\s0
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\s-1{_POSIX_VERSION}\s0 \s-1_SC_VERSION\s0
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.TE
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.RE
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.LP
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.SH RETURN VALUES
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.LP
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.B sysconf(\|)
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returns
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the current variable value
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on success.
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On failure,
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it returns
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\-1
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and sets
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.B errno
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to indicate the error.
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.SH ERRORS
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.TP 15
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.SM EINVAL
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The value of
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.I name
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is invalid.
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.\".SH SEE ALSO
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.\".BR getrlimit (2)
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