8. Finding Files

Sometimes you will need to find files on the system that match given criteria, such as name and file size. This chapter will show you how to find a file when you know only part of the file name, and how to find a file whose name matches a given pattern. You will also learn how to list files and directories by their size and to find the locations of commands.

NOTE: When you want to find files in a directory whose contents match a particular pattern, search through the files with grep---see Searching Text. A method of searching for a given pattern in the contents of files in different directories is given in Running Commands on the Files You Find.

See Info file `find.info', node `Top', for more information on finding files.

8.1 Finding All Files That Match a Pattern		Quickly locating files that match a pattern.
8.2 Finding Files in a Directory Tree		The find tool is for finding files.
8.3 Finding Files in Directory Listings		Finding files in directory listings.
8.4 Finding Where a Command Is Located		Locating a command.

8.1 Finding All Files That Match a Pattern

The simplest way to find files is with GNU locate. Use it when you want to list all files on the system whose full path name matches a particular pattern--for example, all files with the text `audio' somewhere in their full path name, or all files ending with `ogg'; locate outputs a list of all files on the system that match the pattern, giving their full path name. When specifying a pattern, you can use any of the file name expansion characters (see section Specifying File Names with Patterns).

• To find all the files on the system that have the text `audio' anywhere in their name, type:

  $ locate audio RET

• To find all the files on the system whose file names end with the text `ogg', type:

  $ locate *ogg RET

• To find all hidden "dotfiles" on the system, type:

  $ locate /. RET

NOTE: locate searches are not case sensitive.

Sometimes, a locate search will generate a lot of output. Pipe the output to less to peruse it (see section Perusing Text).

8.2 Finding Files in a Directory Tree

Use find to find specific files in a particular directory tree, specifying the name of the directory tree to search, the criteria to match, and--optionally--the action to perform on the found files. (Unlike most other tools, you must specify the directory tree argument before any other options.)

You can specify a number of search criteria, and format the output in various ways; the following sections include recipes for the most commonly used find commands, as well as a list of find's most popular options.

8.2.1 Finding Files in a Directory Tree by Name		The basic find options.
8.2.2 Finding Files in a Directory Tree by Size		Finding files by size.
8.2.3 Finding Files in a Directory Tree by Modification Time		Finding files by date.
8.2.4 Finding Files in a Directory Tree by Owner		Finding files by owner.
8.2.5 Running Commands on the Files You Find		Running commands on the files you find.
8.2.6 Finding Files by Multiple Criteria		A list of find's many options.

8.2.1 Finding Files in a Directory Tree by Name

Use find to find files in a directory tree by name. Give the name of the directory tree to search through, and use the `-name' option followed by the name you want to find.

• To list all files on the system whose file name is `top', type:

  $ find / -name top RET

This command will search all directories on the system to which you have access; if you don't have execute permission for a directory, find will report that permission is denied to search the directory.

The `-name' option is case sensitive; use the similar `-iname' option to find name regardless of case.

• To list all files on the system whose file name is `top', regardless of case, type:

  $ find / -iname top RET

This command would match any files whose name consisted of the letters `top', regardless of case--including `Top', `top', and `TOP'.

Use file expansion characters (see section Specifying File Names with Patterns) to find files whose names match a pattern. Give these file name patterns between single quotes.

• To list all files on the system whose names begin with the characters `top', type:

  $ find / -name 'top*' RET

• To list all files whose names begin with the three characters `top' followed by exactly three more characters, type:

  $ find / -name 'top???' RET

• To list all files whose names begin with the three characters `top' followed by five or more characters, type:

  $ find / -name 'top?????*' RET

• To list all files in your home directory tree that end in `.tex', regardless of case, type:

  $ find ~ -iname '*.tex' RET

• To list all files in the `/usr/share' directory tree with the text `farm' somewhere in their name, type:

  $ find /usr/share -name '*farm*' RET

Use `-regex' in place of `-name' to search for files whose names match a regular expression, or a pattern describing a set of strings (see section Regular Expressions--Matching Text Patterns).

• To list all files in the current directory tree whose names have either the string `net' or `comm' anywhere in their file names, type:

  $ find . -regex '.*\(net\|comm\).*' RET

NOTE: The `-regex' option matches the whole path name, relative to the directory tree you specify, and not just file names.

8.2.2 Finding Files in a Directory Tree by Size

To find files of a certain size, use the `-size' option, following it with the file size to match. The file size takes one of three forms: when preceded with a plus sign (`+'), it matches all files greater than the given size; when preceded with a hyphen or minus sign (`-'), it matches all files less than the given size; with neither prefix, it matches all files whose size is exactly as specified. (The default unit is 512-byte blocks; follow the size with `k' to denote kilobytes or `b' to denote bytes.)

• To list all files in the `/usr/local' directory tree that are greater than 10,000 kilobytes in size, type:

  $ find /usr/local -size +10000k RET

• To list all files in your home directory tree less than 300 bytes in size, type:

  $ find ~ -size -300b RET

• To list all files on the system whose size is exactly 42 512-byte blocks, type:

  $ find / -size 42 RET

Use the `-empty' option to find empty files--files whose size is 0 bytes. This is useful for finding files that you might not need, and can remove.

• To find all empty files in your home directory tree, type:

  $ find ~ -empty RET

NOTE: To find the largest or smallest files in a given directory, output a sorted listing of that directory (see section Finding Files in Directory Listings).

8.2.3 Finding Files in a Directory Tree by Modification Time

To find files last modified during a specified time, use find with the `-mtime' or `-mmin' options; the argument you give with `-mtime' specifies the number of 24-hour periods, and with `-mmin' it specifies the number of minutes.

• To list the files in the `/usr/local' directory tree that were modified exactly 24 hours ago, type:

  $ find /usr/local -mtime 1 RET

• To list the files in the `/usr' directory tree that were modified exactly five minutes ago, type:

  $ find /usr -mmin 5 RET

To specify a range of time, precede the number you give with either a plus sign (`+') to match times that are equal to or greater than the given argument, or a hyphen or minus sign (`-') to match times that are equal to or less than the given argument.

• To list the files in the `/usr/local' directory tree that were modified within the past 24 hours, type:

  $ find /usr/local -mtime -1 RET

• To list the files in the `/usr' directory tree that were modified within the past five minutes, type:

  $ find /usr -mmin -5 RET

Include the `-daystart' option to measure time from the beginning of the current day instead of 24 hours ago.

• To list all of the files in your home directory tree that were modified yesterday, type:

  $ find ~ -mtime 1 -daystart RET

• To list all of the files in the `/usr' directory tree that were modified one year or longer ago, type:

  $ find /usr -mtime +356 -daystart RET

• To list all of the files in your home directory tree that were modified from two to four days ago, type:

  $ find ~ -mtime 2 -mtime -4 -daystart RET

In the preceding example, the combined options `-mtime 2' and `-mtime -4' matched files that were modified between two and four days ago.

To find files newer than a given file, give the name of that file as an argument to the `-newer' option.

• To find files in the `/etc' directory tree that are newer than the file `/etc/motd', type:

  $ find /etc -newer /etc/motd RET

To find files newer than a given date, use the trick described in the find Info documentation: create a temporary file in `/tmp' with touch whose timestamp is set to the date you want to search for, and then specify that temporary file as the argument to `-newer'.

• To list all files in your home directory tree that were modified after May 4 of the current year, type:

  $ touch -t 05040000 /tmp/timestamp RET $ find ~ -newer /tmp/timestamp RET

In this example, a temporary file called `/tmp/timestamp' is written; after the search, you can remove it (see section Removing Files and Directories).

NOTE: You can also find files that were last accessed a number of days after they were modified by giving that number as an argument to the `-used' option. This is useful for finding files that get little use--files matching `-used +100', say, were accessed 100 or more days after they were last modified.

8.2.4 Finding Files in a Directory Tree by Owner

To find files owned by a particular user, give the username to search for as an argument to the `-user' option.

• To list all files in the `/usr/local/fonts' directory tree owned by the user warwick, type:

  $ find /usr/local/fonts -user warwick RET

The `-group' option is similar, but it matches group ownership instead of user ownership.

• To list all files in the `/dev' directory tree owned by the audio group, type:

  $ find /dev -group audio RET

8.2.5 Running Commands on the Files You Find

You can also use find to execute a command you specify on each found file, by giving the command as an argument to the `-exec' option. If you use the string `'{}'' in the command, this string is replaced with the file name of the current found file when the command executes. Mark the end of the command with the string `';''.

• To find all files in the `~/html/' directory tree with an `.html' extension, and output lines from these files that contain the string `organic', type:

  $ find ~/html/ -name '*.html' -exec grep organic '{}' ';' RET

In this example, the command grep organic file is executed for each file that find finds, with file being the name of each file in turn.

To have find pause and confirm execution for each file it finds, use `-ok' instead of `-exec'.

• To remove files from your home directory tree that were accessed more than one year after they were last modified, pausing to confirm before each removal, type:

  $ find ~ -used +365 -ok rm '{}' ';' RET

8.2.6 Finding Files by Multiple Criteria

You can combine many of find's options to find files that match multiple criteria.

• To list files in your home directory tree whose names begin with the string `top', and that are newer than the file `/etc/motd', type:

  $ find ~ -name 'top*' -newer /etc/motd RET

• To compress all the files in your home directory tree that are two megabytes or larger, and that are not already compressed with gzip (having a `.gz' file name extension), type:

  $ find ~ -size +2000000c -regex '.*[^gz]' -exec gzip '{}' ';' RET

The following tables describe many other options you can use with find. The first table lists and describes find's general options for specifying its behavior. As you will see, find can take many different options; see its man page or its info documentation for all of them.

The following table lists and describes find's options for specifying which files to find.

Specify the numeric arguments to these options in one of three ways: preceded with a plus sign (`+') to match values equal to or greater than the given argument; preceded with a hyphen or minus sign (`-') to match values equal to or less than the given argument; or give the number alone to match exactly that value.

The following table lists and describes find's options for specifying what to do with the files it finds.

The following table describes the variables may be used in the format string used by the `-printf' option.

8.3 Finding Files in Directory Listings

The following recipes show how to find the largest and smallest files and directories in a given directory or tree by listing them by size. They also show how to find the number of files in a given directory.

8.3.1 Finding the Largest Files in a Directory		Finding the largest files.
8.3.2 Finding the Smallest Files in a Directory		Finding the smallest files.
8.3.3 Finding the Smallest Directories		Finding the largest directories.
8.3.4 Finding the Largest Directories		Finding the smallest directories.
8.3.5 Finding the Number of Files in a Listing		Counting the number of files you find.

8.3.1 Finding the Largest Files in a Directory

To find the largest files in a given directory, use ls to list its contents with the `-S' option, which sorts files in descending order by their size (normally, ls outputs files sorted alphabetically). Include the `-l' option to output the size and other file attributes.

• To list the files in the current directory, with their attributes, sorted with the largest files first, type:

  $ ls -lS RET

NOTE: Pipe the output to less to peruse it (see section Perusing Text).

8.3.2 Finding the Smallest Files in a Directory

To list the contents of a directory with the smallest files first, use ls with both the `-S' and `-r' options, which reverses the sorting order of the listing.

• To list the files in the current directory and their attributes, sorted from smallest to largest, type:

  $ ls -lSr RET

8.3.3 Finding the Smallest Directories

To output a list of directories sorted by their size--the size of all the files they contain--use du and sort. The du tool outputs directories in ascending order with the smallest first; the `-S' option puts the size in kilobytes of each directory in the first column of output. Give the directory tree you want to output as an option, and pipe the output to sort with the `-n' option, which sorts its input numerically.

• To output a list of the subdirectories of the current directory tree, sorted in ascending order by size, type:

  $ du -S . | sort -n RET

8.3.4 Finding the Largest Directories

Use the `-r' option with sort to reverse the listing and output the largest directories first.

• To output a list of the subdirectories in the current directory tree, sorted in descending order by size, type:

  $ du -S . | sort -nr RET

• To output a list of the subdirectories in the `/usr/local' directory tree, sorted in descending order by size, type:

  $ du -S /usr/local | sort -nr RET

8.3.5 Finding the Number of Files in a Listing

To find the number of files in a directory, use ls and pipe the output to `wc -l', which outputs the number of lines in its input (see section Counting Text).

• To output the number of files in the current directory, type:

  $ ls | wc -l RET 19 $

In this example, the command outputs the text `19', indicating that there are 19 files in the current directory.

Since ls does not list hidden files by default (see section Listing Hidden Files), the preceding command does not count them. Use ls's `-A' option to count dot files as well.

• To count the number of files--including dot files--in the current directory, type:

  $ ls -A | wc -l RET 81 $

This command outputs the text `81', indicating that there are 81 files, including hidden files, in the current directory.

To list the number of files in a given directory tree, and not just a single directory, use find instead of ls, giving the special find predicate `\! -type d' to exclude the listing (and therefore, counting) of directories.

• To list the number of files in the `/usr/share' directory tree, type:

  $ find /usr/share \! -type d | wc -l RET

• To list the number of files and directories in the `/usr/share' directory tree, type:

  $ find /usr/share | wc -l RET

• To list the number of directories in the `/usr/share' directory tree, type:

  $ find /usr/share \! -type f | wc -l RET

8.4 Finding Where a Command Is Located

Use which to find the full path name of a tool or application from its base file name; when you give the base file name as an option, which outputs the absolute file name of the command that would have run had you typed it. This is useful when you are not sure whether or not a particular command is installed on the system.

• To find out whether perl is installed on your system, and, if so, where it resides, type:

  $ which perl RET /usr/bin/perl

In this example, which output `/usr/bin/perl', indicating that the perl binary is installed in the `/usr/bin' directory.

NOTE: This is also useful for determining "which" binary would execute, should you type the name, since some systems may have different binaries of the same file name located in different directories. In that case, you can use which to find which one would execute.