ps.1

linux下获取一些环境信息的代码

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.TH PS 1 "July 28, 2004" "Linux" "Linux User's Manual"
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.\"
.SH NAME
ps \- report a snapshot of the current processes.
.SH SYNOPSIS
\fBps\fR [\fIoptions\fR]
.PP
.PP
.SH DESCRIPTION
.B ps
displays information about a selection of the active processes.
If you want a repetitive update of the selection and the
displayed information, use\ \fItop\fR(1) instead.
.P
This version of \fBps\fR accepts several kinds of options:
.PD 0
.IP 1 4
UNIX options, which may be grouped and must be preceded by a dash.
.IP 2 4
BSD options, which may be grouped and must not be used with a dash.
.IP 3 4
GNU long options, which are preceded by two dashes.
.PD
.PP
Options of different types may be freely mixed, but conflicts can appear.
There are some synonymous options, which are functionally identical, due
to the many standards and \fBps\fR implementations that this \fBps\fR is
compatible with.
.P
Note that "\fBps\ \-aux\fR" is distinct from "\fBps\ aux\fR".
The POSIX and UNIX standards require that "\fBps\ \-aux\fR" print all
processes owned by a user named "x", as well as printing all processes
that would be selected by the \fB\-a\fR option. If the user named "x" does
not exist, this \fBps\fR may interpret the command as "\fBps\ aux\fR"
instead and print a warning. This behavior is intended to aid in
transitioning old scripts and habits. It is fragile, subject to change,
and thus should not be relied upon.
.P
By default, \fBps\fR selects all processes
with the same effective user ID (euid=EUID) as the current user
and
associated with the same terminal as the invoker.
It displays the process ID (pid=PID),
the terminal associated with the process (tname=TTY),
the cumulated CPU time in [dd\-]hh:mm:ss format (time=TIME),
and the executable name (ucmd=CMD).
Output is unsorted by default.
.P
The use of BSD\-style options will add process state (stat=STAT) to the
default display and show the command args (args=COMMAND) instead of the
executable name. You can override this with the \fBPS_FORMAT\fR
environment variable. The use of BSD\-style options will also change the
process selection to include processes on other terminals (TTYs) that
are owned by you; alternately, this may be described as setting the
selection to be the set of all processes filtered to exclude
processes owned by other users or not on a terminal. These effects
are not considered when options are described as being "identical" below,
so \fB\-M\fR will be considered identical to \fBZ\fR and so on.
.P
Except as described below, process selection options are additive.
The default selection is discarded, and then the selected processes
are added to the set of processes to be displayed.
A\ process will thus be shown if it meets any of the given
selection criteria.
.PP
.\" """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.SH "EXAMPLES"
.TP 3
To see every process on the system using standard syntax:
.B ps\ \-e
.br
.B ps\ \-ef
.br
.B ps\ \-eF
.br
.B ps\ \-ely
.TP
To see every process on the system using BSD syntax:
.B ps\ ax
.br
.B ps\ axu
.TP
To print a process tree:
.B ps\ -ejH
.br
.B ps\ axjf
.TP
To get info about threads:
.B ps\ -eLf
.br
.B ps\ axms
.TP
To get security info:
.B ps\ -eo euser,ruser,suser,fuser,f,comm,label
.br
.B ps\ axZ
.br
.B ps\ -eM
.TP
To see every process running as root (real\ &\ effective\ ID) in user format:
.B ps\ \-U\ root\ \-u\ root\ u
.TP
To see every process with a user\-defined format:
.B ps\ \-eo\ pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
.br
.B ps\ axo\ stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm
.br
.B ps\ \-eopid,tt,user,fname,tmout,f,wchan
.TP
Print only the process IDs of syslogd:
.B ps\ \-C\ syslogd\ \-o\ pid=
.TP
Print only the name of PID 42:
.B ps\ \-p\ 42\ \-o\ comm=
.PP
.PP
.\" """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.SH "SIMPLE PROCESS SELECTION"
.opt \-A
Select all processes.  Identical to \fB\-e\fR.

.opt \-N
Select all processes except those that fulfill the specified conditions.
(negates the selection) Identical to \fB\-\-deselect\fR.

.opt T
Select all processes associated with this terminal.  Identical to the
\fBt\fR option without any argument.

.opt \-a
Select all processes except session leaders (see \fIgetsid\fR(2)) and
processes not associated with a terminal.

.opt a
Lift the BSD\-style "only yourself" restriction, which is imposed upon
the set of all processes when some BSD\-style (without\ "\-") options
are used or when the \fBps\fR personality setting is BSD\-like.
The set of processes selected in this manner is
in addition to the set of processes selected by other means.
An alternate description is that this option causes \fBps\fR to
list all processes with a terminal (tty),
or to list all processes when used together with the \fBx\fR option.

.opt \-d
Select all processes except session leaders.

.opt \-e
Select all processes.  Identical to \fB\-A\fR.

.\" Current "g" behavior: add in the session leaders, which would
.\" be excluded in the sunos4 personality. Supposed "g" behavior:
.\" add in the group leaders -- at least according to the SunOS 4
.\" man page on the FreeBSD site. Uh oh. I think I had tested SunOS
.\" though, so maybe the code is correct.
.opt g
Really all, even session leaders.  This flag is obsolete and may be
discontinued in a future release. It is normally implied by the \fBa\fR flag,
and is only useful when operating in the sunos4 personality.

.opt r
Restrict the selection to only running processes.

.opt x
Lift the BSD\-style "must have a tty" restriction, which is imposed upon
the set of all processes when some BSD\-style (without\ "\-") options
are used or when the \fBps\fR personality setting is BSD\-like.
The set of processes selected in this manner is
in addition to the set of processes selected by other means.
An alternate description is that this option causes \fBps\fR to
list all processes owned by you (same EUID as \fBps\fR),
or to list all processes when used together with the \fBa\fR option.

.opt \-\-deselect
Select all processes except those that fulfill the specified conditions.
(negates the selection) Identical to \fB\-N\fR.

.\" """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.PD
.PP
.SH "PROCESS SELECTION BY LIST"
These options accept a single argument in the form of a blank\-separated
or comma\-separated list.  They can be used multiple times.
For\ example:\ \fBps\ \-p\ "1\ 2"\ \-p\ 3,4\fR
.P
.opt \-C \ cmdlist
Select by command name.
.br
This selects the processes whose executable name is given in
\fIcmdlist\fR.

.opt \-G \ grplist
Select by real group ID (RGID) or name.
.br
This selects the processes whose real group name or ID is in the
\fIgrplist\fR list.  The real group ID identifies the group of the user
who created the process, see \fIgetgid\fR(2).

.opt U \ userlist
Select by effective user ID (EUID) or name.
.br
This selects the processes whose effective user name
or ID is in \fIuserlist\fR.
The effective user\ ID describes the user whose file
access permissions are used by the process
(see\ \fIgeteuid\fR(2)).
Identical to \fB\-u\fR and\ \fB\-\-user\fR.

.opt \-U \ userlist
select by real user ID (RUID) or name.
.br
It selects the processes whose real user name or ID is in the
\fIuserlist\fR list.
The real user ID identifies the user who created the process,
see\ \fIgetuid\fR(2).

.opt \-g \ grplist
Select by session OR by effective group name.
.br
Selection by session is specified by many standards,
but selection by effective group is the logical behavior that
several other operating systems use.
This \fBps\fR will select by session when the list
is completely numeric (as\ sessions\ are).
Group ID numbers will work only when some group names are also specified.
See the \fB\-s\fR and \fB\-\-group\fR options.

.opt p \ pidlist
Select by process ID.  Identical to \fB\-p\fR and\ \fB\-\-pid\fR.

.opt \-p \ pidlist
Select by PID.
.br
This selects the processes whose process ID numbers appear in
\fIpidlist\fR.  Identical to \fBp\fR and\ \fB\-\-pid\fR.

.opt \-s \ sesslist
Select by session ID.
.br
This selects the processes
with a session ID specified in\ \fIsesslist\fR.

.opt t \ ttylist
Select by tty.  Nearly identical to \fB\-t\fR and \fB\-\-tty\fR,
but can also be used with an empty \fIttylist\fR to indicate
the terminal associated with \fBps\fR.
Using the \fBT\fR option is considered cleaner than using \fBT\fR with
an\ empty\ \fIttylist\fR.

.opt \-t \ ttylist
Select by tty.
.br
This selects the processes associated with the terminals
given in \fIttylist\fR.
Terminals (ttys, or screens for text output) can be specified in several
forms: /dev/ttyS1, ttyS1, S1.
A\ plain "\-" may be used to select processes not attached to any terminal.

.opt \-u \ userlist
Select by effective user ID (EUID) or name.
.br
This selects the processes whose effective user name or ID is in
\fIuserlist\fR.  The effective user ID describes the user whose file
access permissions are used by the process (see\ \fIgeteuid\fR(2)).
Identical to \fBU\fR and \fB\-\-user\fR.

.opt \-\-Group \ grplist
Select by real group ID (RGID) or name.  Identical to \fB\-G\fR.

.opt \-\-User \ userlist
Select by real user ID (RUID) or name.  Identical to \fB\-U\fR.

.opt \-\-group \ grplist
Select by effective group ID (EGID) or name.
.br
This selects the processes whose effective group name or ID is in
\fIgrouplist\fR.  The effective group ID describes the group whose file
access permissions are used by the process (see\ \fIgeteuid\fR(2)).
The \fB\-g\fR option is often an alternative to\ \fB\-\-group\fR.

.opt \-\-pid \ pidlist
Select by process\ ID.  Identical to \fB\-p\fR\ and\ \fBp\fR.

.opt \-\-ppid \ pidlist
Select by parent process\ ID.
This selects the processes
with a parent\ process\ ID in \fRpidlist\fR.
That\ is, it selects processes that are children
of those listed in \fRpidlist\fR.

.opt \-\-sid \ sesslist
Select by session\ ID.  Identical to\ \fB\-s\fR.

.opt \-\-tty \ ttylist
Select by terminal.  Identical to \fB\-t\fR and\ \fBt\fR.

.opt \-\-user \ userlist
Select by effective user ID (EUID) or name.
Identical to \fB\-u\fR and\ \fBU\fR.

.opt \-\fI123\fR
Identical to \fB\-\-sid\ \fI123\fR.

.opt \fI123\fR
Identical to \fB\-\-pid\ \fI123\fR.

.\" """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.PD
.PP
.SH "OUTPUT FORMAT CONTROL"
These options are used to choose the information displayed by \fBps\fR.
The output may differ by personality.
.PP

.opt \-F
extra full format. See the \fB\-f\fR option, which \fB\-F\fR implies.

.opt \-O \ format
is like \fB\-o\fR, but preloaded with some default columns.
Identical to \fB\-o\ pid,\fIformat\fB,state,tname,time,command\fR
or \fB\-o\ pid,\fIformat\fB,tname,time,cmd\fR, see\ \fB\-o\fR\ below.

.opt O \ format
is preloaded \fBo\fR (overloaded).
.br
The BSD \fBO\fR option can act like \fB\-O\fR (user\-defined output
format with some common fields predefined) or can be used to specify
sort order.  Heuristics are used to determine the behavior of this
option. To ensure that the desired behavior is obtained (sorting or
formatting), specify the option in some other way
(e.g. with \fB\-O\fR or \fB\-\-sort\fR).
When used as a formatting option, it is identical to \fB\-O\fR, with the
BSD\ personality.

.opt \-M
Add a column of security data. Identical to \fBZ\fR. (for\ SE\ Linux)

.opt X
Register format.

.opt Z
Add a column of security data. Identical to \fB\-M\fR. (for\ SE\ Linux)

.opt \-c
Show different scheduler information for the \fB\-l\fR option.

.opt \-f
does full\-format listing. This option can be combined with many
other UNIX\-style options to add additional columns. It also causes
the command arguments to be printed. When used with \fB\-L\fR, the
NLWP (number of threads) and LWP (thread ID) columns will be added.
See the \fBc\fR option, the format keyword \fBargs\fR, and the
format keyword \fBcomm\fR.

.opt j
BSD job control format.

.opt \-j
jobs format

.opt l
display BSD long format.

.opt \-l
long format. The \fB\-y\fR option is often useful with this.

.opt o \ format
specify user\-defined format.  Identical to \fB\-o\fR and
\fB\-\-format\fR.

.opt \-o \ format
user\-defined format.
.br
\fIformat\fR is a single argument in the form of a
blank\-separated or comma\-separated list, which offers
a way to specify individual output columns.
The recognized keywords are described in the \fBSTANDARD FORMAT
SPECIFIERS\fR section below.
Headers may be
renamed (\fBps\ \-o\ pid,ruser=RealUser\ \-o\ comm=Command\fR) as desired.
If all column headers are empty (\fBps\ \-o\ pid=\ \-o\ comm=\fR) then the
header line will not be output. Column width will increase as
needed for wide headers; this may be used to widen up columns
such as WCHAN (\fBps\ \-o\ pid,wchan=WIDE\-WCHAN\-COLUMN\ \-o\ comm\fR).
Explicit width control (\fBps\ opid,wchan:42,cmd\fR) is offered too.
The behavior of \fBps\ \-o\ pid=X,comm=Y\fR varies with personality;
output may be one column named "X,comm=Y" or two columns
named "X" and "Y". Use multiple \fB\-o\fR options when in doubt.
Use the \fBPS_FORMAT\fR environment variable to specify a default
as desired; DefSysV and DefBSD are macros that may be used to
choose the default UNIX or BSD columns.

.opt s
display signal format

.opt u
display user\-oriented format

.opt v
display virtual memory format

.opt \-y
Do not show flags; show rss in place of addr.
This option can only be used with \fB\-l\fR.

.opt \-\-format \ format
user\-defined format.  Identical to \fB\-o\fR and \fBo\fR.

.opt \-\-context
Display security context format. (for\ SE\ Linux)

.\" """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.PD
.PP
.SH "OUTPUT MODIFIERS"

.\"  .TP
.\"  .B C
.\"  use raw CPU time for %CPU instead of decaying average

.opt \-H
show process hierarchy (forest)

.opt N \ namelist
Specify namelist file.  Identical to \fB\-n\fR, see \fB\-n\fR above.

.opt O \ order
Sorting order. (overloaded)
.br
The BSD \fBO\fR option can act like \fB\-O\fR (user\-defined output
format with some common fields predefined) or can be used to specify
sort order.  Heuristics are used to determine the behavior of this
option. To ensure that the desired behavior is obtained (sorting or
formatting), specify the option in some other way (e.g. with \fB\-O\fR
or \fB\-\-sort\fR).

For sorting, obsolete BSD \fBO\fR option syntax is
\fBO\fR[\fB+\fR|\fB\-\fR]\fIk1\fR[,[\fB+\fR|\fB\-\fR]\fIk2\fR[,...]].
It orders the processes listing according to the multilevel sort specified by
the sequence of one\-letter short keys \fIk1\fR, \fIk2\fR, ... described
in the \fBOBSOLETE SORT KEYS\fR section below.
The\ "+" is currently optional,
merely re\-iterating the default direction on a key,
but may help to distinguish an \fBO\fR sort from an \fBO\fR format.
The\ "\-" reverses direction only on the key it precedes.

.opt S
Sum up some information, such as CPU usage, from dead child processes
into their parent. This is useful for examining a system where a
parent process repeatedly forks off short\-lived children to do work.

.opt c
Show the true command name. This is derived from the name of the