Investigate

In this section

• 🔍️ Investigate

  Ressources

  1# in crontab or tmux session - take every hour a track of the memory usage
  2for i in {1..24} ; do echo -n "===================== " ; date ; free -m ; top -b -n1 | head -n 15 ; sleep 3600; done >> /var/log/SYSADM/memory.log &
  

  Hardware

  Logs

  Health Checks

• 🚩 Compare

  Compare staffs

  • Compare two jar files:

  1diff -W200 -y  <(unzip -vqq file1.jar | awk '{ if ($1 > 0) {printf("%s\t%s\n", $1, $8)}}' | sort -k2) <(unzip -vqq  file2.jar | awk '{ if ($1 > 0) {printf("%s\t%s\n", $1, $8)}}' | sort -k2)
  

• 🚩 Files

  Find a process blocking a file

  • with fuser:

   1fuser  -m  </dir or /files>  # Find process blocking/using this directory or files. 
   2fuser -cu  </dir or /files>  # Same as above but add the user  
   3fuser -kcu </dir or /files>  # Kill process      
   4fuser -v  -k -HUP -i ./      # Send HUP signal to process
   5			
   6# Output will send you <PID + letter>, here is the meaning:
   7#   c  current directory.
   8#   e  executable being run.
   9#   f  open file.  (omitted in default display mode).
  10#   F  open file for writing. (omitted in default display mode).
  11#   r  root directory.
  12#   m  mmap'ed file or shared library.
  

  • with lsof ( = list open file):

  1lsof +D /var/log          # Find all files blocked with the process and user.
  2lsof -a +L1 <mountpoint>  # Process blocking a FS.
  3lsof -c ssh -c init       # Find files open by thoses processes.
  4lsof -p 1753              # Find files open by PID process.
  5lsof -u root              # Find files open by user.
  6lsof -u ^user             # Find files open by user except this one.
  7kill -9 `lsof -t -u toto` # kill user's processes.  (option -t output only PID).
  

  • MacGyver method:

  1#When you have no fuser or lsof: 
  2find /proc/*/fd -type f -links 0 -exec ls -lrt {} \;