todo

linux下获取一些环境信息的代码

-------------------------- general ------------------------

Consider using glibc obstacks for memory allocation.

Implement /usr/proc/bin tools like Solaris has.
The prstat command is interesting, like top in batch mode.
SCO has a pstat command.

Don't these really belong in the procps package?
         killall   pstree   fuser   lsof   who
(they are maintained elsewhere, which causes version problems)

OpenBSD has a pfind command.

Cache results of dev_to_tty.

---------------------- kernel -------------------------

Add an "adopted child" flag to mark processes that are not
natural children of init. This can make --forest work better.

Supply better data for top's CPU state display. Currently top has
to subtract old numbers from new numbers and divide that result by
the number of processors. The kernel won't even supply the number
of processors in a portable way.

Supply data for the ADDR and JOBC fields.

Support & supply data for SL and RE.

Add a /proc/*/tty symlink to eliminate guessing when /proc/*/fd is
not accessable.

Add /proc/*/.bindata files to avoid string parsing. It should be an array
of 64-bit values on all machines. New entries go on the end and obsolete
ones get filled in with something logical -- entries must never be deleted!

Add all the stuff Solaris has. This would also replace ptrace.

---------------------- w --------------------------

The LOGIN@ column sometimes has a space in it. This makes correct
scripting difficult.

Verify that DNS control does not give a user the power to specify
arbitrary data for the FROM column. (could set root's VGA color map!)

---------------------- vmstat --------------------------

Extract /proc/diskstats parsing from vmstat into libproc somewhere.

--------------------- libproc ----------------------

Stop storing fields with duplicate info (often different
units: kB and pages, seconds and jiffies) in the proc_t struct.

---------------------- top -------------------------

Share more stuff with ps.

don't truncate long usernames

have a --config option

---------------- ps for now, maybe move to libproc ------------------

With forest output and a tty named /dev/this_is_my_tty, the position
of the command name gets messed up. (we print too many spaces) (fixed?)

Fix missing stuff for these formats: FB_j FB_l FB_v HP_f HP_l HP_fl JFMT OL_m
(jobc,cpu,sl,re,cpu,prmgrp,m_swap,m_share,vm_lib,m_dt)
Note that "cpu" has two meanings.

Add Beowulf support. This is ugly, since the current patches use a
daemon to collect info and add a HOST field after the PID field.

Query optimizer, put cheap/required process selection first.

Avoid reading both /proc/*/status and /proc/*/stat.

Support printing the client hostname (the FROM that w(1) uses) in place
of a pty.

Disambiguate narrow tty info. (/dev/tty7 == /dev/pts/7 now)
1------8     1--4
ttyS2        S2
ttyI31       I31
pts/7        7        Short form could be /999.
pts/9999     9999     Short form could just be trunctuated to /999.
tty7         7        Short form could be vc-7.
tty63        63       Short form could be vc63.

Internationalization, as specified by XPG3, Volume 1, Commands and Utilities.
(and suggested by Unix98) LC_TIME affects date format.

----------------------- ps -----------------------

Add an option to select all processes that a user can kill.
(related to RUID, EUID, tty, etc. -- but maybe ignore root power)

Add a nice display option for killing things.
ruser,euser,ppid,pid,pmem,stime,args

For RT stuff:
pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm

For job control:
stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm

Make the column alignment algorithm support this:
    FOO BAR
    8 44444
    453  45
    45 2989
    63666 0
    34  333
(useful for the UNIX tty and time values, since the time might look
like 100-10:40:32 for old processes and the tty might have extra room)

Improve long sort/format specifiers documentation and fill in the missing
code as much as the kernel can support. Make sure that memory amounts are in
pages when they should be and in kB when they should be, not backwards.

output encoding: UTF8 --nul --null

Make BSD formats use non-standard BSD time format, at least when it
doesn't violate the "no whitespace" rule.

Better unmangling of '?' as a tty. The shell destroys '?' when there
is a filename that matches. If the argument seems like garbage,
check for a file that might have screwed up the '?'.

If the 'O' option is given something already implied by 'O',
assume the user wanted a sorting option.

Conflict:
Digital THREAD is user,pcpu,pri,scnt,wchan,usertime,systime
AIX     THREAD is uname,pid,ppid,tid,S,C,PRI,scount,WCHAN,F,tty,bnd,comm
AIX looks like this:
         USER   PID  PPID  TID S  C PRI SC   WCHAN   FLAG   TTY BND  CMD