ps.html

unix 下的C开发手册,还用详细的例程。

A process that has exited and has a parent, but has not
yet been waited for by the parent, is marked
<b>defunct</b>.
<p>
Under the option
<b>-f</b>,
<i>ps</i>
tries to determine the command name
and arguments given when the process was created
by examining memory or the swap area.
Failing this, the command name, as it
would appear without the option
<b>-f</b>,
is written in square brackets.
<p>
The
<b>-o</b>
option allows the output format to be
specified under user control.
<p>
The format specification must be a list of names
presented as a single argument,
blank-
or comma-separated.
Each variable has a default header.
The default header can be overridden
by appending an equals sign and the new
text of the header.
The rest of the characters in the argument
will be used as the header text.
The fields specified will be written in the order specified
on the command line, and should be arranged in columns in the output.
The field widths will be selected by the system to be at least
as wide as the header text (default or overridden value).
If the header text is null, such as
<b>-o</b>
user=,
the field width will be at least as wide as the
default header text.
If all header text fields are null,
no header line will be written.
<p>
The following names are recognised in the POSIX locale:
<dl compact>

<dt><b>ruser</b><dd>The real user ID of the process.
This will be the textual user ID,
if it can be obtained and the field width permits,
or a decimal representation otherwise.

<dt><b>user</b><dd>The effective user ID of the process.
This will be the textual user ID,
if it can be obtained and the field width permits,
or a decimal representation otherwise.

<dt><b>rgroup</b><dd>The real group ID of the process.
This will be the textual group ID,
if it can be obtained and the field width permits,
or a decimal representation otherwise.

<dt><b>group</b><dd>The effective group ID of the process.
This will be the textual group ID,
if it can be obtained and the field width permits,
or a decimal representation otherwise.

<dt><b>pid</b><dd>The decimal value of the process ID.

<dt><b>ppid</b><dd>The decimal value of the parent process ID.

<dt><b>pgid</b><dd>The decimal value of the process group ID.

<dt><b>pcpu</b><dd>The ratio of CPU time used recently
to CPU time available in the same period, expressed as a percentage.
The meaning of &quot;recently&quot; in this context is unspecified.
The CPU time available is determined in an unspecified manner.

<dt><b>vsz</b><dd>The size of the process in (virtual) memory in kilobytes as a decimal integer.

<dt><b>nice</b><dd>The decimal value of the system scheduling priority of the process.
See
<i><a href="nice.html">nice</a></i>.

<dt><b>etime</b><dd>In the POSIX locale, the elapsed time since the process
was started, in the form:
<pre>
<code>
<b>[[</b><i>dd</i>-<b>]</b><i>hh</i>:<b>]</b><i>mm</i>:<i>ss
</i></code>
</pre>
where
<i>dd</i>
will represent the number of days,
<i>hh</i>
the number of hours,
<i>mm</i>
the number of minutes, and
<i>ss</i>
the number of seconds.
The
<i>dd</i>
field will be a decimal integer.
The
<i>hh</i>,
<i>mm</i>
and
<i>ss</i>
fields will be two-digit decimal integers padded on the left with zeros.

<dt><b>time</b><dd>In the POSIX locale, the cumulative CPU time of the process in the form:
<pre>
<code>
<b>[</b><i>dd</i>-<b>]</b><i>hh</i>:<i>mm</i>:<i>ss
</i></code>
</pre>

The
<i>dd</i>,
<i>hh</i>,
<i>mm</i>
and
<i>ss</i>
fields will be as described in the
<b>etime</b>
specifier.

<dt><b>tty</b><dd>The name of the controlling terminal of the process
(if any) in the same format used by the
<i><a href="who.html">who</a></i>
utility.

<dt><b>comm</b><dd>The name of the command being executed
(<i>argv</i>[0]
value) as a string.

<dt><b>args</b><dd>The command with all its arguments as a string.
The implementation may truncate this value to the field width;
it is implementation-dependent whether any further truncation occurs.
It is unspecified whether the string represented is a
version of the argument list as it was
passed to the command when it started, or is a
version of the arguments as they may
have been modified by the application.
Applications cannot depend on being able to
modify their argument list and having
that modification be reflected in the output of
<i>ps</i>.

</dl>
<p>
Any field need not be meaningful in all implementations.
In such a case a hyphen
(-)
should be output in place of the field value.
<p>
Only
<b>comm</b>
and
<b>args</b>
are allowed to contain
blank characters;
all others are not.
Any implementation-dependent variables will be specified in the
system documentation
along with the default header
and indicating if the field may contain
blank characters.
<p>
The following table
specifies the default header to be used in the POSIX locale
corresponding to each format specifier.
<pre>
<table  bordercolor=#000000 border=1 align=center><tr valign=top><th align=center><b>Format Specifier</b>
<th align=center><b>Default Header</b>
<th align=center><b>Format Specifier</b>
<th align=center><b>Default Header</b>
<tr valign=top><td align=left>args
<td align=left>COMMAND
<td align=left>ppid
<td align=left>PPID
<tr valign=top><td align=left>comm
<td align=left>COMMAND
<td align=left>rgroup
<td align=left>RGROUP
<tr valign=top><td align=left>etime
<td align=left>ELAPSED
<td align=left>ruser
<td align=left>RUSER
<tr valign=top><td align=left>group
<td align=left>GROUP
<td align=left>time
<td align=left>TIME
<tr valign=top><td align=left>nice
<td align=left>NI
<td align=left>tty
<td align=left>TT
<tr valign=top><td align=left>pcpu
<td align=left>%CPU
<td align=left>user
<td align=left>USER
<tr valign=top><td align=left>pgid
<td align=left>PGID
<td align=left>vsz
<td align=left>VSZ
<tr valign=top><td align=left>pid
<td align=left>PID
<td align=left>&nbsp;
<td align=left>&nbsp;
</table>
</pre>
<h6 align=center><xref table="Variable Names and Default Headers in <I>ps</i>"></xref>Table: Variable Names and Default Headers in <i>ps</i></h6>
</blockquote><h4><a name = "tag_001_014_1812">&nbsp;</a>STDERR</h4><blockquote>
Used only for diagnostic messages.
</blockquote><h4><a name = "tag_001_014_1813">&nbsp;</a>OUTPUT FILES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_1814">&nbsp;</a>EXTENDED DESCRIPTION</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_1815">&nbsp;</a>EXIT STATUS</h4><blockquote>
The following exit values are returned:
<dl compact>

<dt>0<dd>Successful completion.

<dt>&gt;0<dd>An error occurred.

</dl>
</blockquote><h4><a name = "tag_001_014_1816">&nbsp;</a>CONSEQUENCES OF ERRORS</h4><blockquote>
Default.
</blockquote><h4><a name = "tag_001_014_1817">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
Things can change while
<i>ps</i>
is running; the snapshot it gives is only true for an instant,
and might not be accurate by the time it is displayed.
<p>
The
<b>args</b>
format specifier is allowed to produce a truncated
version of the command arguments.
In some implementations, this information
is no longer available when the
<i>ps</i>
utility is executed.
<p>
If the field width is too narrow to display a textual ID,
the system may use a numeric version.
Normally, the system would be expected to choose large
enough field widths, but if a large number of fields
were selected to write, it might squeeze fields
to their minimum sizes to fit on one line.
One way to ensure adequate width for the textual IDs
is to override the
default header for a field to make it larger than
most or all user or group names.
<p>
There is no special quoting mechanism for header text.
The header text is the rest of the argument.
If multiple header changes are needed,
multiple
<b>-o</b>
options can be used, such as:
<pre>
<code>
ps -o "user=User Name" -o pid=Process\ ID
</code>
</pre>
<p>
On some systems, especially multi-level secure systems,
<i>ps</i>
may be severely restricted and produce information
only about child processes owned by the user.
<br>
</blockquote><h4><a name = "tag_001_014_1818">&nbsp;</a>EXAMPLES</h4><blockquote>
The command:
<pre>
<code>
ps -o user,pid,ppid=MOM -o args
</code>
</pre>
writes at least the following in the POSIX locale:
<pre>
<dl compact><dt> <dd>
<table <tr valign=top><th align=right>USER
<th align=left>PID
<th align=right>MOM
<th align=left>COMMAND
<tr valign=top><td align=right>helene
<td align=left>34
<td align=right>12
<td align=left>ps -o uid,pid,ppid=MOM -o args
</table>
</dl>
</pre>
The contents of the
<b>COMMAND</b>
field need not be the same in all implementations, due
to possible truncation.
</blockquote><h4><a name = "tag_001_014_1819">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_001_014_1820">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="kill.html">kill</a></i>,
<i><a href="nice.html">nice</a></i>,
<i><a href="renice.html">renice</a></i>.
</blockquote><hr size=2 noshade>
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