If you are feeling lazy and need to search for some file or directory in your whole system, then locate
might be your best friend. It can find things super fast from thousands of items with the help of a database created earlier and usually updated automatically once a day.
locate
almost works like the librarian in a library. When you ask the librarian for a book, he/she can find it for you in the entire library very efficiently because the books are sorted by some order.
locate
does not locate the file/directories on your system directly but on a database of absolute pathnames which are gathered beforehand. This database has an index, which makes finding things very fast.
Using locate
is very simple. Let's get started by first installing it.
Installing
In most modern Linux distributions the locate
command is available via the plocate
and mlocate
packages. Both packages gives us two commands: locate
and updatedb
.
I recommend installing the plocate
package because it's faster than mlocate
and almost a drop-in-replacement for mlocate
. While all variants of locate
s are more or less the same, in this article we will discuss about plocate
particularly.
plocate
is available in the official repositores of the following distros and can be installed like below:
# Arch
sudo pacman -S plocate
# Debian / Ubuntu
sudo apt install plocate
# Fedora
sudo dnf install plocate
Usage
Creating the database with updatedb
Before using it you will need to create it's database by running updatedb
like below, if you don't want to wait for the system to do it for you:
sudo updatedb
It will take some time. Usually updatedb
is run once a day automatically by your system to keep the database updated.
Since the database is not guaranteed to hold the most recent info about your syestem, you will may notice that very recent files/directories do not show up when using locate
. To overcome this, it’s possible to run the updatedb
command manually like we did before.
How to use the locate
command
The general syntax of locate
command is:
locate [OPTION]... PATTERN...
Based on the given patterns and options, locate
performs a quick database search of absolute pathnames of files and directories that are accessible to the user in the entire system.
It can be used with or with out options. First let's see it's usage without any options.
Without options
To find out all the pathnames containing the substring bin
we can enter bin
as pattern:
locate bin
It will display a long list of absolute pathnames containing the pattern bin
in them:
/bin
/sbin
/etc/bindresvport.blacklist
/etc/binfmt.d
/etc/libinput
/etc/ca-certificates/extracted/edk2-cacerts.bin
/etc/profile.d/perlbin.csh
/etc/profile.d/perlbin.sh
.
.
.
Now if we want only the pathnames that contains both bin
and zip
we can enter both as patterns:
locate bin zip
This time the output will be significantly less somewhat like below:
/usr/bin/bunzip2
/usr/bin/bzip2
/usr/bin/bzip2recover
/usr/bin/funzip
/usr/bin/gunzip
/usr/bin/gzip
/usr/bin/unzip
/usr/bin/unzipsfx
/usr/bin/zipgrep
/usr/bin/zipinfo
We can also use glob patterns(aka wildcard patterns). In this case it's important to quote the pattern to prevent the shell from expanding them. For example:
locate '*.md'
It lists only the pathnames that ends with .md
. These are the first few items from my system:
/home/ashutosh/.cache/tldr/pages/common/bg.md
/home/ashutosh/.cache/tldr/pages/common/cat.md
/home/ashutosh/.cache/tldr/pages/common/exec.md
/home/ashutosh/.cache/tldr/pages/common/fg.md
/home/ashutosh/.cache/tldr/pages/common/git.md
/home/ashutosh/.cache/tldr/pages/common/neofetch.md
/home/ashutosh/.cache/tldr/pages/common/tldr.md
/home/ashutosh/.cache/tldr/pages/common/ts-node.md
/home/ashutosh/.cache/tldr/pages/common/vim.md
/home/ashutosh/.cache/tldr/pages/linux/pacman.md
Tip: If the output of locate
is long you can pipe it to less
for better viewing:
locate '*.md' | less
Note that it's not anymore a substring match. So in the language of glob patterns, locate bin
is equivalent of:
locate '*bin*'
Other wildcards that can be used like this are ?
for matching any single character and []
for character classes. See What are wildcards and globbing? for more details on these wildcards.
With options
Here we will see the most commonly used options:
-c
or --count
Adding -c
or --count
option displays the number of matched items. For example the following will print the number of javascript files on your system that are accessible to you:
locate -c '*.js'
-l
or --limit
With the -l
or --limit
option you can set the upper limit for searching items. For example:
locate -l 10 '*.css'
This will only display at most 10 pathnames.
-i
or --ignore-case
By default locate
performs case-sensitive search. To do a case-insensitive search add the -i
or --ignore-case
flag:
locate -i An-Old-Post.md
-e
or --existing
After the most recent database update, if some file/directory deleted, it will still show up, if searched for. To not include such items add the -e
or --existing
flag.
Note that newly added files after the most recent database update will not show up. To show them, the database must be updated.
Options for regular expressions
If you want to search using a POSIX basic regular expression, -r
or --regexp
are the options. For example to count for all JavaScript and JSON files, the command will be:
locate --regexp -c '\.\(js\|json\)$'
If you want to search using a POSIX extended regular expression, then use the option --regex
. So the above command can be written much more cleanly like below with --regex
:
locate --regex -c '\.(js|json)$'
Note that these options will treat all given patterns to be the corresponding type of regular expressions.
Summary
# for updating the database
sudo updatedb
# finding by matching a pattern string as substring in the pathnames
locate cat.jpg
# all pathnames will be displayed that satisfy both patterns
locate bin python
# finding using wildcard patterns
locate '*.jpg'
# count all jpg files
locate -c '*.jpg'
# display only first 10 jpg files
locate -l 10 '*.jpg'
# Case-insensitive search
locate -i 'cat.jpg'
# For not including deleted files after most recent database update
locate -e 'cat.jpg'
# POSIX basic regular expression
locate -r '\.\(js\|json\)$'
# POSIX extended regular expression
locate --regex '\.(js|json)$'
For further info see locate
's man page by entering man plocate
.
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