Know more about a process

Today, I would like to introduce some ways to get more information of a process, and hope those can help in trouble-shooting and debugging.

List environment variables

To list the environment variables of a process you can issue the command:
ps ewww pid
E.g.:

ahlam@oxygen:~/test/malloc$ ps ewww 4752
PID TTY      STAT   TIME COMMAND
4752 pts/2    Ss+    0:00 bash USER=ahlam HOME=/home/ahlam DESKTOP_SESSION=default GDM_XSERVER_LOCATION=loca
l GTK_IM_MODULE=gcin LOGNAME=ahlam USERNAME=ahlam GDM_LANG=en_HK.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/u
sr/sbin:/usr/bin:/sbin:/bin:/usr/bin/X11:/usr/games DISPLAY=:0.0 LANG=en_HK.UTF-8 XMODIFIERS=@im=gcin XAUTHOR
ITY=/home/ahlam/.Xauthority SHELL=/bin/bash GDMSESSION=default QT_IM_MODULE=gcin PWD=/home/ahlam SSH_AUTH_SOC
K=/tmp/ssh-nRdglP4521/agent.4521 SSH_AGENT_PID=4563 DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-ix9My5o6
DJ,guid=8abd2646dc897f03d1cfb07e3a3d4b00 GTK_RC_FILES=/etc/gtk/gtkrc:/home/ahlam/.gtkrc-1.2-gnome2 SESSION_MA
NAGER=local/oxygen:/tmp/.ICE-unix/4521 GNOME_KEYRING_SOCKET=/tmp/keyring-fXmYul/socket GNOME_DESKTOP_SESSION_
ID=Default TERM=xterm COLORTERM=gnome-terminal WINDOWID=31457489

List out the threads of a process

ps ms pid
E.g:

ahlam@oxygen:~/test/malloc$ ps ms 4752
UID   PID          PENDING          BLOCKED          IGNORED           CAUGHT STAT TTY        TIME COMMAND
1000  4752 0000000000000000                -                -                - -    pts/2      0:00 bash
1000     - 0000000000000000 0000000000000000 0000000000384004 000000004b813efb Ss+  -          0:00 -

Print the memory map

To list the memory map of a process, you can use the pmap command. It lists out the mapped memory regions and the purpose of the memory regions. It also lists out the .so files loaded by the process.
pmap pid
E.g:

ahlam@oxygen:~/test/malloc$ pmap 4752
4752:   bash
08048000    644K r-x--  /bin/bash
080e9000     20K rw---  /bin/bash
080ee000   1804K rw---    [ anon ]
b7c94000     36K r-x--  /lib/tls/i686/cmov/libnss_files-2.4.so
b7c9d000      8K rw---  /lib/tls/i686/cmov/libnss_files-2.4.so
b7c9f000     32K r-x--  /lib/tls/i686/cmov/libnss_nis-2.4.so
b7ca7000      8K rw---  /lib/tls/i686/cmov/libnss_nis-2.4.so
b7ca9000     72K r-x--  /lib/tls/i686/cmov/libnsl-2.4.so
b7cbb000      8K rw---  /lib/tls/i686/cmov/libnsl-2.4.so
b7cbd000      8K rw---    [ anon ]
b7cbf000     28K r-x--  /lib/tls/i686/cmov/libnss_compat-2.4.so
b7cc6000      8K rw---  /lib/tls/i686/cmov/libnss_compat-2.4.so
b7cd7000    204K r----  /usr/lib/locale/en_HK.utf8/LC_CTYPE
b7d0a000      4K r----  /usr/lib/locale/en_HK.utf8/LC_NUMERIC
b7d0b000      4K r----  /usr/lib/locale/en_HK.utf8/LC_TIME
b7d0c000    860K r----  /usr/lib/locale/en_HK.utf8/LC_COLLATE
b7de3000      8K rw---    [ anon ]
b7de5000   1204K r-x--  /lib/tls/i686/cmov/libc-2.4.so
b7f12000      8K r----  /lib/tls/i686/cmov/libc-2.4.so
b7f14000      8K rw---  /lib/tls/i686/cmov/libc-2.4.so
b7f16000     12K rw---    [ anon ]
b7f19000      8K r-x--  /lib/tls/i686/cmov/libdl-2.4.so
b7f1b000      8K rw---  /lib/tls/i686/cmov/libdl-2.4.so
b7f1d000    220K r-x--  /lib/libncurses.so.5.5
b7f54000     32K rw---  /lib/libncurses.so.5.5
b7f5c000      4K rw---    [ anon ]
b7f5d000      4K r----  /usr/lib/locale/en_HK.utf8/LC_MONETARY
b7f5e000      4K r----  /usr/lib/locale/en_HK.utf8/LC_MESSAGES/SYS_LC_MESSAGES
b7f5f000      4K r----  /usr/lib/locale/en_HK.utf8/LC_PAPER
b7f60000      4K r----  /usr/lib/locale/en_HK.utf8/LC_NAME
b7f61000      4K r----  /usr/lib/locale/en_HK.utf8/LC_ADDRESS
b7f62000      4K r----  /usr/lib/locale/en_HK.utf8/LC_TELEPHONE
b7f63000      4K r----  /usr/lib/locale/en_HK.utf8/LC_MEASUREMENT
b7f64000     28K r--s-  /usr/lib/gconv/gconv-modules.cache
b7f6b000      4K r----  /usr/lib/locale/en_HK.utf8/LC_IDENTIFICATION
b7f6c000      8K rw---    [ anon ]
b7f6e000    100K r-x--  /lib/ld-2.4.so
b7f87000      8K rw---  /lib/ld-2.4.so
bfa1c000     88K rw---    [ stack ]
ffffe000      4K -----    [ anon ]
total     5528K

/proc/pid

In proc/pid directory, it contains much information of a process.

ahlam@oxygen:~/test/malloc$ ls -l /proc/4752
total 0
dr-xr-xr-x 2 ahlam ahlam 0 2007-04-19 20:17 attr
-r-------- 1 ahlam ahlam 0 2007-04-19 20:17 auxv
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 19:57 cmdline
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 cpuset
lrwxrwxrwx 1 ahlam ahlam 0 2007-04-19 18:20 cwd -> /home/ahlam/test/malloc
-r-------- 1 ahlam ahlam 0 2007-04-19 19:58 environ
lrwxrwxrwx 1 ahlam ahlam 0 2007-04-19 20:17 exe -> /bin/bash
dr-x------ 2 ahlam ahlam 0 2007-04-19 19:57 fd
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:06 maps
-rw------- 1 ahlam ahlam 0 2007-04-19 20:17 mem
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 mounts
-r-------- 1 ahlam ahlam 0 2007-04-19 20:17 mountstats
-rw-r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 oom_adj
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 oom_score
lrwxrwxrwx 1 ahlam ahlam 0 2007-04-19 20:17 root -> /
-rw------- 1 ahlam ahlam 0 2007-04-19 20:17 seccomp
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 smaps
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 19:57 stat
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 statm
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 19:57 status
dr-xr-xr-x 3 ahlam ahlam 0 2007-04-19 20:17 task
-r--r--r-- 1 ahlam ahlam 0 2007-04-19 20:17 wchan

For details, please man proc.