find

Search for files in a directory hierarchy.

How:

cd ~find

• Find all files under ~/find (including subdirectories) end with .bak:

  find . -name '*.bak'

  	./dir_1/d.bak
  	./a.bak
  	./b.bak

• Find all directories under /usr:

  find ~/usr -type d

  	.
  	./dir_1
  	./dir_2
  	./dir_2/dir_2.1

• Find all files under current directory with name end with '.log' and have been modified for less than 1 day. Copy all files to /tmp.

  find . -ctime -1 -name '*.bak' -exec cp {} /tmp ;

  The brace-pair "{}" represents the file(s) found. In fact, the command "cp {} /tmp" will be executed for each file found. If there are 3 files found: a.bak, b.bak, and c.bak, three commands are executed:

  1. cp a.bak /tmp
  2. cp b.bak /tmp
  3. cp c.bak /tmp

Real-life example:

Some quality applications/programs do not clean the temporary files created after use. One of the admin task is to remove them. Here we remove files in /tmp which have not been modified for more than 7 days.

find /tmp -depth -mtime +7 -exec /bin/rm -rf {} ;

There are many options available for find. Its a very powerful tool in system administration. For detail, see its manpage.