Locating files

You can locate all files with a specified name, permissions setting, size, type, owner, or last access or modification date using find(1). Use this command to locate seldom-used or excessively large files, files owned by a particular user, temporary files, core files, and any unused a.out files.

The syntax of find is:

find pathname option

pathname is the pathname of the directory to search. The find command searches recursively, downward through all the directories under the named directory, for files that match the criteria specified by option.

Finding specific files by name (-name)

For example, to locate and display all files named temp recursively in the /usr directory, enter:

find /usr -name temp -print

Finding files of a certain size (-size)

For example, to locate and print a list of all the files greater than three blocks in size in all the directories (/ and below), enter:

find / -size +3 -print

Finding files by owner (-user)

For example, to find all files in the /work directory owned by olivier, enter:

find /work -user olivier -print

Finding files of a certain type (-type)

For example, to locate all the directories in /usr/spool/uucp, enter:

find /usr/spool/uucp -type d -print

Finding files by permissions (-perm onum)

onum is the octal number used with chmod(1).
For example, to locate and display all the files in the /usr directory that give all users read, write, and execute permissions (onum is 0777), enter:

find /usr -perm 0777 -print

See also:

• ``Finding temporary files''

• ``Executing commands based on find output''

Finding temporary files

Use find with the -name option to locate temporary files for removal.

A temporary file contains data created as an intermediate step during execution of a program. This file may be left behind if a program contained an error or was prematurely stopped by the user. The name of a temporary file depends on the program that created it. In most cases, the user has no use for temporary files, and you can safely remove them.

Use find to locate files with a specific name, such as temp. For example, to locate and display all files named temp under the /usr directory, enter:

find /usr -name temp -print

When searching for temporary files, it is a good idea to search for files that have not been accessed for a reasonable period of time. For example, to find all temp files in the /usr directory that have not been accessed for one week (-atime +7), enter:

find /usr -name temp -atime +7 -print

Once you locate the temp files, you can remove them automatically using the -exec option to find. See ``Executing commands based on find output''.

Executing commands based on find output

You can execute a specific shell command on the files that find locates using the -exec option. The most common use of -exec is to locate a group of files and then remove them.

For example, to find all the core files in the /usr filesystem that have not been accessed in seven days and remove them, enter:

find /usr -name core -atime +7 -exec rm "{}" \;

As another example, when you retire a user, use find to locate all the files owned by that user, back them up, and then remove them from the system. To do this, enter:

find / -user edwarda -print | cpio -ovBc > /dev/rfd0
find / -user edwarda -exec rm "{}" \;

The first command locates all the files owned by user edwarda and copies the files to a floppy disk archive. The second command locates the files and then removes them. For more information on copying files to an archive, see cpio(1).

To specify that find prompt you with the command line that find generates before executing the shell command on each file, use -ok in place of -exec:

find / -user edwarda -ok rm "{}" \;

In this case, find prompts you with:

   <rm ... /u/edwarda/billboard >?

Another common use of find with the -exec option is to locate all the files that belong to a particular group and change them. For example, if a user changes groups, you can use find to locate and change all their files to the new group:

find / -user edwarda -exec chgrp pubs "{}" \;

You can use find to change the owner of a group of files. For example, if you retire a user and you want to transfer ownership of their files to another user, use this command:

find / -user edwarda -exec chown earnestc "{}" \;

Using this construction to execute a command on a large group of files can be very slow because the -exec option forks a separate process for each file in the list. A more efficient method for doing this is to use xargs(1) in place of -exec. The xargs command forks fewer processes to execute the command on the entire group of files.

The following example illustrates how to use the xargs construction with find:

find / -user edwarda -print | xargs chown earnestc

This command accomplishes the same thing as the previous example, only much more efficiently.