Finding files

Find a file on the file system

find - search for files in a directory hierarch

• find [paths] EXPRESSIONS
• paths = directories which are searched
• paths must precede expression

Find a file or a directory

• -type restricts the search on the type of entries.

  • f regular file
  • d directory
  • l symbolic link

find . -type f

Find files by name

• -name pattern Base of file name (the path with the leading directories removed) matches shell pattern pattern.
• The metacharacters (*, ?, and []) are supported.

Don't forget to enclose the pattern in quotes in order to protect it from expansion by the shell.

• -iname Like -name, but the match is case insensitive.

find . -name '*.fasta'

Find files by date

• -atime n File was last accessed n*24 hours ago. When find figures out how many 24-hour periods ago the file was last accessed, any fractional part is ignored, so to match -atime +1, a file has to have been accessed at least two days ago.
• -ctime n File was created n*24 hours ago.
• -mtime n File was last modified n*24 hours ago
• -newer file_b File was last modified more recently than file_b.

#find every files which was read at most 3 days ago or
find . -atime 2
#find every files created today
find . -ctime 0

Find files by owner

• -user uname File is owned by user uname (numeric user ID allowed)
• -uid n File's numeric user ID is n.
• -group gname File belongs to group gname (numeric group ID allowed).
• -gid n File's numeric group ID is n.

Find files and execute a command on the result

• -exec specifies that the following command template should be executed for each matching file.
• {} is replaced by the current file name
• ; ends the command to execute

#find each fasta file in my DataBio directory
#containing the string 'ABCD'
find ~/DataBio -name '*.fasta' -exec grep -H ABCD {} \;

Exercises

1. on your virtual machine, find all the files created on tuesday in your home directory.
2. on your virtual machine, find all the files in DataBio or in subtree which contains 'IL2' use -exec.
3. connect to central-bio and find all the files that are owned by one of your unit members in your unit directory.
4. in unix_training project dir, find files without any extensions (HINT: ! negates an expression for instance find . ! -type f match all link and dir)

Find files on a file system