busybox/procps/ps.posix

This is what POSIX 2003 says about ps:

By default, ps shall select  all processes with the same effective user
ID as the current user and the same controlling terminal as the invoker

ps [-aA][-defl][-G grouplist][-o format]...[-p proclist][-t termlist]
[-U userlist][-g grouplist][-n namelist][-u userlist]

-a     Write information for all processes associated  with  terminals.
       Implementations may omit session leaders from this list.

-A     Write information for all processes.

-d     Write information for all processes, except session leaders.

-e     Write information for all processes.  (Equivalent to -A.)

-f     Generate  a  full  listing. (See the STDOUT section for the con-
       tents of a full listing.)

-g  grouplist
       Write information for processes whose session leaders are  given
       in grouplist. The application shall ensure that the grouplist is
       a single argument in the form of a  <blank>  or  comma-separated
       list.

-G  grouplist
       Write  information for processes whose real group ID numbers are
       given in grouplist. The application shall ensure that the  grou-
       plist  is  a  single argument in the form of a <blank> or comma-
       separated list.

-l     Generate a long listing. (See STDOUT for the contents of a  long
       listing.)

-n  namelist
       Specify the name of an alternative system namelist file in place
       of the default. The name of the default file and the format of a
       namelist file are unspecified.

-o  format
       Write information according to the format specification given in
       format.  Multiple -o options can be specified; the format speci-
       fication shall be interpreted as the  <space>-separated concate-
       nation of all the format option-arguments.

-p  proclist
       Write  information  for  processes  whose process ID numbers are
       given in proclist. The application shall ensure  that  the  pro-
       clist  is  a  single argument in the form of a <blank> or comma-
       separated list.

-t  termlist
       Write information for processes associated with terminals  given
       in termlist. The application shall ensure that the termlist is a
       single argument in the form  of  a  <blank>  or  comma-separated
       list.  Terminal identifiers shall be given in an implementation-
       defined format.    On  XSI-conformant  systems,  they  shall  be
       given  in  one of two forms: the device's filename (for example,
       tty04) or, if the device's filename starts with  tty,  just  the
       identifier following the characters tty (for example, "04" ).

-u  userlist
       Write  information  for processes whose user ID numbers or login
       names are given in userlist. The application shall  ensure  that
       the  userlist  is  a single argument in the form of a <blank> or
       comma-separated list. In the  listing,  the  numerical  user  ID
       shall be written unless the -f option is used, in which case the
       login name shall be written.

-U  userlist
       Write information for processes whose real user  ID  numbers  or
       login  names are given in userlist. The application shall ensure
       that the userlist is a single argument in the form of a  <blank>
       or comma-separated list.

With  the  exception of -o format, all of the options shown are used to
select processes. If any are  specified,  the  default  list  shall  be
ignored  and ps shall select the processes represented by the inclusive
OR of all the selection-criteria options.

The  -o option allows the output format to be specified under user con-
trol.

The application shall ensure that the format specification is 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 shall be used as the  header  text.  The
fields specified shall be written in the order specified on the command
line, and should be arranged in columns in the output. The field widths
shall  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
-o  user=,  the  field  width  shall be at least as wide as the default
header text. If all header text fields are null, no header  line  shall
be written.

ruser  The  real user ID of the process. This shall be the textual user
       ID, if it can be obtained and the field width permits, or a dec-
       imal representation otherwise.

user   The  effective user ID of the process. This shall be the textual
       user ID, if it can be obtained and the field width permits, or a
       decimal representation otherwise.

rgroup The  real  group  ID  of  the process. This shall be the textual
       group ID, if it can be obtained and the field width permits,  or
       a decimal representation otherwise.

group  The effective group ID of the process. This shall be the textual
       group ID, if it can be obtained and the field width permits,  or
       a decimal representation otherwise.

pid    The decimal value of the process ID.

ppid   The decimal value of the parent process ID.

pgid   The decimal value of the process group ID.

pcpu   The ratio of CPU time used recently to CPU time available in the
       same  period,  expressed  as  a  percentage.  The   meaning   of
       "recently"  in  this context is unspecified. The CPU time avail-
       able is determined in an unspecified manner.

vsz    The size of the process in (virtual) memory in 1024  byte  units
       as a decimal integer.

nice   The decimal value of the nice value of the process; see nice() .

etime  In the POSIX locale, the elapsed  time  since  the  process  was
       started, in the form: [[dd-]hh:]mm:ss

time   In the POSIX locale, the cumulative CPU time of the  process  in
       the form: [dd-]hh:mm:ss

tty    The name of the controlling terminal of the process (if any)  in
       the same format used by the who utility.

comm   The  name  of  the  command being executed ( argv[0] value) as a
       string.

args   The command with all its arguments as a string. The  implementa-
       tion may truncate this value to the field width; it is implemen-
       tation-defined 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 ps.

Any field need not be meaningful in all implementations. In such a case
a hyphen ( '-' ) should be output in place of the field value.

Only  comm  and  args  shall be allowed to contain <blank>s; all others
shall not.

The following table specifies the default header  to  be  used  in  the
POSIX locale corresponding to each format specifier.

    Format Specifier Default Header Format Specifier Default Header
    args             COMMAND        ppid             PPID
    comm             COMMAND        rgroup           RGROUP
    etime            ELAPSED        ruser            RUSER
    group            GROUP          time             TIME
    nice             NI             tty              TT
    pcpu             %CPU           user             USER
    pgid             PGID           vsz              VSZ
    pid              PID

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 -o options can be used, such as:

        ps -o "user=User Name" -o pid=Process\ ID
1	This is what POSIX 2003 says about ps:
2
3	By default, ps shall select all processes with the same effective user
4	ID as the current user and the same controlling terminal as the invoker
5
6	ps [-aA][-defl][-G grouplist][-o format]...[-p proclist][-t termlist]
7	[-U userlist][-g grouplist][-n namelist][-u userlist]
8
9	-a Write information for all processes associated with terminals.
10	Implementations may omit session leaders from this list.
11
12	-A Write information for all processes.
13
14	-d Write information for all processes, except session leaders.
15
16	-e Write information for all processes. (Equivalent to -A.)
17
18	-f Generate a full listing. (See the STDOUT section for the con-
19	tents of a full listing.)
20
21	-g grouplist
22	Write information for processes whose session leaders are given
23	in grouplist. The application shall ensure that the grouplist is
24	a single argument in the form of a <blank> or comma-separated
25	list.
26
27	-G grouplist
28	Write information for processes whose real group ID numbers are
29	given in grouplist. The application shall ensure that the grou-
30	plist is a single argument in the form of a <blank> or comma-
31	separated list.
32
33	-l Generate a long listing. (See STDOUT for the contents of a long
34	listing.)
35
36	-n namelist
37	Specify the name of an alternative system namelist file in place
38	of the default. The name of the default file and the format of a
39	namelist file are unspecified.
40
41	-o format
42	Write information according to the format specification given in
43	format. Multiple -o options can be specified; the format speci-
44	fication shall be interpreted as the <space>-separated concate-
45	nation of all the format option-arguments.
46
47	-p proclist
48	Write information for processes whose process ID numbers are
49	given in proclist. The application shall ensure that the pro-
50	clist is a single argument in the form of a <blank> or comma-
51	separated list.
52
53	-t termlist
54	Write information for processes associated with terminals given
55	in termlist. The application shall ensure that the termlist is a
56	single argument in the form of a <blank> or comma-separated
57	list. Terminal identifiers shall be given in an implementation-
58	defined format. On XSI-conformant systems, they shall be
59	given in one of two forms: the device's filename (for example,
60	tty04) or, if the device's filename starts with tty, just the
61	identifier following the characters tty (for example, "04" ).
62
63	-u userlist
64	Write information for processes whose user ID numbers or login
65	names are given in userlist. The application shall ensure that
66	the userlist is a single argument in the form of a <blank> or
67	comma-separated list. In the listing, the numerical user ID
68	shall be written unless the -f option is used, in which case the
69	login name shall be written.
70
71	-U userlist
72	Write information for processes whose real user ID numbers or
73	login names are given in userlist. The application shall ensure
74	that the userlist is a single argument in the form of a <blank>
75	or comma-separated list.
76
77	With the exception of -o format, all of the options shown are used to
78	select processes. If any are specified, the default list shall be
79	ignored and ps shall select the processes represented by the inclusive
80	OR of all the selection-criteria options.
81
82	The -o option allows the output format to be specified under user con-
83	trol.
84
85	The application shall ensure that the format specification is a list of
86	names presented as a single argument, <blank> or comma-separated. Each
87	variable has a default header. The default header can be overridden by
88	appending an equals sign and the new text of the header. The rest of
89	the characters in the argument shall be used as the header text. The
90	fields specified shall be written in the order specified on the command
91	line, and should be arranged in columns in the output. The field widths
92	shall be selected by the system to be at least as wide as the header
93	text (default or overridden value). If the header text is null, such as
94	-o user=, the field width shall be at least as wide as the default
95	header text. If all header text fields are null, no header line shall
96	be written.
97
98	ruser The real user ID of the process. This shall be the textual user
99	ID, if it can be obtained and the field width permits, or a dec-
100	imal representation otherwise.
101
102	user The effective user ID of the process. This shall be the textual
103	user ID, if it can be obtained and the field width permits, or a
104	decimal representation otherwise.
105
106	rgroup The real group ID of the process. This shall be the textual
107	group ID, if it can be obtained and the field width permits, or
108	a decimal representation otherwise.
109
110	group The effective group ID of the process. This shall be the textual
111	group ID, if it can be obtained and the field width permits, or
112	a decimal representation otherwise.
113
114	pid The decimal value of the process ID.
115
116	ppid The decimal value of the parent process ID.
117
118	pgid The decimal value of the process group ID.
119
120	pcpu The ratio of CPU time used recently to CPU time available in the
121	same period, expressed as a percentage. The meaning of
122	"recently" in this context is unspecified. The CPU time avail-
123	able is determined in an unspecified manner.
124
125	vsz The size of the process in (virtual) memory in 1024 byte units
126	as a decimal integer.
127
128	nice The decimal value of the nice value of the process; see nice() .
129
130	etime In the POSIX locale, the elapsed time since the process was
131	started, in the form: [[dd-]hh:]mm:ss
132
133	time In the POSIX locale, the cumulative CPU time of the process in
134	the form: [dd-]hh:mm:ss
135
136	tty The name of the controlling terminal of the process (if any) in
137	the same format used by the who utility.
138
139	comm The name of the command being executed ( argv[0] value) as a
140	string.
141
142	args The command with all its arguments as a string. The implementa-
143	tion may truncate this value to the field width; it is implemen-
144	tation-defined whether any further truncation occurs. It is
145	unspecified whether the string represented is a version of the
146	argument list as it was passed to the command when it started,
147	or is a version of the arguments as they may have been modified
148	by the application. Applications cannot depend on being able to
149	modify their argument list and having that modification be
150	reflected in the output of ps.
151
152	Any field need not be meaningful in all implementations. In such a case
153	a hyphen ( '-' ) should be output in place of the field value.
154
155	Only comm and args shall be allowed to contain <blank>s; all others
156	shall not.
157
158	The following table specifies the default header to be used in the
159	POSIX locale corresponding to each format specifier.
160
161	Format Specifier Default Header Format Specifier Default Header
162	args COMMAND ppid PPID
163	comm COMMAND rgroup RGROUP
164	etime ELAPSED ruser RUSER
165	group GROUP time TIME
166	nice NI tty TT
167	pcpu %CPU user USER
168	pgid PGID vsz VSZ
169	pid PID
170
171	There is no special quoting mechanism for header text. The header text
172	is the rest of the argument. If multiple header changes are needed,
173	multiple -o options can be used, such as:
174
175	ps -o "user=User Name" -o pid=Process\ ID