anchor.diff:  *provides info on the symbols used in an object file or executable. by default, nm shows the symbol: value, type and name.*
   
   basic syntax:
  -[source,bash]
  +----
   $ nm 
  +----
   
   [NOTE]
   ====
  
positive.code: = Notes
  :author: jonny rhea
  :doctype: notes
  :encoding: utf-8
  :lang: en
  :toc: left
  :date: 5/12/2013
  :numbered:
  
  [index]
  
negative.code: [source,bash]
  $ find / -mmin -10 –type f
  
  === watch
  Use the watch command to monitor a process every .1 secs
  
  [source,bash]
  ----
  watch -e -n .1 'if ps cax | grep -w 'foo'; then exit 0; else exit 1; fi'
  ----
  
  [index]
  == linux system info
  
  report file system disk space usage (human readable):
  ----
  $ df -h
  ----
  
  processor info:
  ----
  $ more /proc/cpuinfo
  ----
  
  memory info:
  ----
  $ more /proc/meminfo
  ----
  
  check to see if Linux is 32 or 64bit:
  ----
  $ getconf LONG_BIT
  ----
  
  distribution info:
  ----
  $ lsb_release
  ----
  
  list all packages installed:
  ----
  $ dpkg -l
  ----
  
  find the 25 largest dirs starting at the current dir:
  ----
  $ du –xk |sort –n |tail -25
  ----
  
  show what processes are using which ports:
  ----
  $ netstat -tulpn
  ----
  
  [index]
  == linux ipc
  === ipcs
  *provides information on system inter process communication.*
  
  ----
  $ ipcs
  
  ------ Shared Memory Segments --------
  key        shmid      owner      perms      bytes      nattch     status     
  0x6112703c 32769        me         666        15600      2  
  
  ------ Semaphore Arrays --------
  key        semid      owner      perms      nsems     
  
  ------ Message Queues --------
  key        msqid      owner      perms      used-bytes   messages    
  
  ----
  
  [TIP]
  ====
  use the following options to filter the information displayed:
  
  * m => shared memory
  * q => message queues
  * s => semaphores
  ====
  
  to find out what process is attached to shared memory use the -p option:
  
  ----
  $ ipcs -mp
  ------ Shared Memory Creator/Last-op --------
  shmid      owner      cpid       lpid     
  32769      me         3265       3290       
  
  $ ps -ef | grep 3290
   3290  3289  1 17:28 ?        00:00:12 /usr/local/java/bin/java -jar ~/foo/foo.jar bar 
   11587 3290  3 17:41 ?        00:00:00 ~/foo/bar
  ----
  
  === ipcrm
  *use this command to remove shared memory, message queue, or semaphore.*
  
  remove shared memory by id
  ---
  $ ipcs -m <shmid>
  ---
  
  remove shared memory by key
  ---
  $ ipcs -M <key>
  ---
  
  [index]
  == linux system configuration
  check and repair filesystem:
  ----
  $ fsck /dev/sda1
  ----
  
  change the frequency of filesys checks on startup:
  ----
  $ tune2fs –c <some number> /dev/sda1
  ----
  
  to change the login manager edit:
  ****
  