shell usage tips

• ctrl + w
  delete a word before cursor

• ctrl + a
  cursor move to beginning

• ctrl + r
  search for history command

• ctrl + k
  delete characters after cursor

• ctrl + u
  delete the whole line

• ctrl + e
  move to the end of line

• ctrl + b
  move back one character

• ctrl + f
  move forward one character

• use bash -x scriptname to debug and see what is under going

shell command

• find
  commonly used switches:
  [ -name , -iname] -iname ignoring case sensitive
  [-size] +20M, -5G
  [-atime, -ctime, -mtime] unit is day +2 1 -3
  [-amin, -cmin, -mmin] unit is minute +2 1 -3
  [-type] f: regular file d: directory
  [-print0] process with filename contains null character
  [-maxdepth, -mindepth] find at most/least level

• xargs
  [-0] process with filename contains null character
  [-Ireplace_str] eg: xargs -Ifile ls -l file
  [-P] how many processed to execute command, if specified with 0, run as many process as possible to deal with.
  [-r] don't exec command if standard input is empty

• combine find and xargs
  eg:
  find /tmp -maxdepth 1 -type f -name \* -print0 | xargs -0 -P 0 -Ifile cp file ~/jk
  descrption:
  find all regular files in /tmp(not include subdirs) and copy them to jk directory as fast as possible

• grep
  [-r] search recursively(include subdirs)
  [-i] ignore case sensitive
  [-w] match the whole world
  [-n] print the line number that matches
  [-v] invert match
  [-c] count how many matches

• lsof
  [-u] list all files that a user opened
  [-i] list all processes that use a specific port. eg: ls -i TCP:22
  [-p] list all opened files by process ID
  [-c] find out files opened by some particular daemon
  [lsof /path/to/file] list processes opened by specific file

• netstat
  [-a] list all connections
  [-t] list tcp connections
  [-u] list udp connections
  [-l] list sockets in listening state
  [-p] show the PID and name of the program to which each socket belongs.
  [netstat -tulpn] frequently used combinations

• du
  [-sh] the size of a file. eg: du -sh Documents

• cut
  [-d] delemiter
  [-f] fields that want to
  In hello.txt: i have a pen

cut -d ' ' -f 2,3 hello.txt

output: have a

reference:

1. http://www.thegeekstuff.com/2012/08/lsof-command-examples
2. http://www.ibm.com/developerworks/aix/library/au-lsof.html
3. http://webcache.googleusercontent.com/search?q=cache:http://www.unixmantra.com/2013/12/xargs-all-in-one-tutorial-guide.html