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Linux query file command: 1, locate, used to find files that meet the criteria, syntax "locate [select parameters] [style]"; 2, find, used to find files in the specified directory, syntax "find [OPTION]. [find path] [find condition] [processing Action]".

The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

There are two common commands for linux to query files:

Locate

Find

Locate

Locate allows users to quickly search for specified files in the file system. The method is to first establish a database that includes all the file names and paths in the system, and then when looking for it, you only need to query the database without actually going deep into the file system. In the general distribution, the establishment of the database is automatically executed in crontab.

1. Command format:

Locate [Select parameters] [style]

2. Command function:

The locate command can quickly find the files when searching the database. Locate is a fuzzy search, the database is updated by the updatedb program, and the updatedb is periodically established by cron daemon. The locate command searches the database faster than the whole hard disk data, but the worse thing is that the files found by locate may not be found if they are recently created or renamed. In the default value, updatedb will run once a day. The setting value can be updated by modifying the crontab. (etc/crontab)

Locate is designated to be used to search for files that meet the criteria. It will store files and directory names in the database. When locate queries files, it will search / var/lib/mlocate/mlocage.db to find files or directories that meet the criteria of the template style. Special characters (such as "*" or "?" can be used. If the template is specified as kcpa*ner, locate will find all files or directories that start with a string of kcpa and end with ner. If the name is kcpartner, if the directory name is kcpa_ner, it will list all files in the directory, including subdirectories.

Locate instruction and find search file function is similar, but locate is through the update program to build an index database of all files and directory information in the hard disk, in the implementation of loacte directly to find the index, the query speed will be faster, the index database is generally managed by the operating system, but you can also directly issue update to force the system to modify the index database immediately.

3. Command parameters:

-e will be excluded from the scope of search.

-1 if it is 1. Then start safe mode. In safe mode, users do not see files that cannot be seen by permissions. This starts to slow down because locate must go to the actual file system to obtain file permission data.

-f exclude specific file systems, for example, we are not reasonable to put files in the proc file system in the database.

-Q quiet mode, no error message is displayed.

-n displays at most n outputs.

-r use the regular expression to do the search condition.

-o specify the name of the data inventory.

-d specify the path to the database

-h display auxiliary message

-V displays the version message of the program

4. Examples of use:

Example 1: search all files that start with sh in the etc directory

[root@CentOS7 ~ #] locate / etc/sh / etc/shadow/etc/shadow-/etc/shells [root@centos7 ~ #] locate-r "/ etc/\ sh" # regular, anchor prefix / etc/shadow/etc/shadow-/etc/shells [root@centos7 ~ #]

Example 2: ignore case

[root@centos7 #] locate-I ~ / d/root/Desktop/root/Documents/root/Downloads/root/d1/root/dd/var/lib/pcp/pmdas/root/domain.h [root@centos7 ~ #]

Example 3: update the database

[root@centos7 ~ #] locate ~ / a/root/anaconda-ks.cfg [root@centos7 ~ #] updatedb[ root @ centos7 ~ #] locate ~ / a/root/a.sh/root/anaconda-ks.cfg [root@centos7 ~ #]

Find

1. Main uses:

The find command is a real-time lookup tool that completes the search of files by traversing the specified path; when using this command, if no parameters are selected, then look for subdirectories and files in the current directory and display them; in addition, any string before the parameters will be regarded as the directory name you want to find. Because it is a real-time traversal search, find has the following characteristics: accurate real-time search, slow search may only search directories where the user has read and execute permissions.

2.find syntax:

Find path: specify a specific target path. Default is the current directory.

Search criteria: the specified search criteria, such as file name, size, type, permissions, etc.; the default is to find all files under the specified path

Processing action: operate on files that meet the criteria, and output to the screen by default

3. Search criteria:

Look up based on file name and inode

Search according to the owner and group.

Find by file type

Search according to logical combination conditions

Find based on file size

Look for it according to the timestamp

Find based on permissions

4. Processing actions:

-print: default action, displayed to the screen

-ls: similar to the ls-l command on the found file

-delete: delete the found file

-fls file: all the long format information found is saved to the specified file

-ok COMMMAND {}\; executes the command specified by COMMAND for each file found, and interactively asks the user for confirmation

-exec COMMAND {}\; execute the command specified by COMMAND for each file found

{}: used to reference the name of the file to which it is found

When find passes the found file to the command specified later, the file that finds all the symbolic conditions is passed to the following command at once.

Some commands cannot accept too many parameters, and command execution may fail. Use xargs to avoid this problem.

Find | xargs COMMAND

5. Common parameters:

File name and inode class:

-name "file name": glob is supported, *,?, [], [^]

-iname "file name": case-insensitive

-inum n: search by inode number

-somefile name: same inode number file

-links n: files with n links

-regex "PATTERN": matches the entire file path string with PATTERN, not just the file name

Belong to the main group class:

-user USERNAME: find files whose owner is the specified user (UID)

-group GROUPNAME: find files that belong to the specified group (GID)

-uid UserID: find the file whose owner is the specified UID number

-gid GroupID: find files with the specified GID number in the group

-nouser: find files without owners

-nogroup: find files that do not belong to a group

File type class:

B block (buffered) special

C character (unbuffered) special

D directory

P named pipe (FIFO) f regular file

L symbolic link

S socket

Logical combination condition class:

Combination conditions:

And:-a

Or:-o

Non:-not!

Morgan's law:

(non-P) or (non-Q) = non (P and Q)

(non-P) and (non-Q) = non (P or Q)

File size class:

-size [+ | -] # UNIT commonly used units: KMagna M UNIT G # UNIT: (#-1 oo #] such as: 5m means (4m Magi 5m)-# UNIT: [0mae 5m] for example:-5m means [0jue 5m] + # UNIT: (#, oo) for example: + 5m means (6m Magneo)

The explanation about the file size class: why-size 5m is still looking for the exact 5m but the expression (4m pr 5m). What does the size of the file mean? Does it mean the size of the file data or the size after including the metadata? does it make sense for you to find the size of the metadata? However, the size of the file must include the size of metadata, and we usually consider the size of the file data when looking for files with file size; in addition, it is not meaningful to accurately find files of a certain size; so the size here will float by 1 unit.

Timestamp class:

In "days":-atime [+ | -] # #: [#, # + 1) + #: [# + 1Magneoo)-#: [0Mae #)-mtime-ctime in "minutes":-amin-mmin-cmin

With regard to the explanation of the timestamp class: why-atime 3 represents [3jue 4), this is easy to explain. The time we are talking about here refers to a period of time rather than a time. A "day" and a "minute" both refer to a period of time, and only the half-closed and half-open interval of [3jue 4) can fully represent the third day.

Permission class:

-perm [/ | -] MODE MODE: exact matching permissions / MODE: as long as one of the permissions of any type of object can match, belong to or relationship. In the past,'+ 'was used to replace CentOS 7 with' /'- MODE: each type of object must have the specified permission at the same time, belonging to the relationship 0: does not care

Example:

Find-perm 644 means to strictly match the files of 644

Find-perm + 222means that any type of user has write permission to match.

Find-perm-222indicates that only write permissions are strictly matched, that is, each user must have write permissions

Find-perm-002indicates that only the write permissions of the other user are strictly matched

6. Examples of use:

Example 1: back up the configuration file to the specified directory and add the extension. org

[root@localhost] # find. -name "* .conf"-exec cp-r {} / testdir/ {} .org\; [root@localhost ~] # cd / testdir/ [root@localhost testdir] # lsa.conf.org b.conf.org [root@localhost testdir] #

Example 2. Prompt to delete temporary files owned by young that have existed for more than 3 days.

[root@localhost ~] # find / tmp-ctime + 3-user young-exec rm-fr {}\; [root@localhost ~] #

Example 3: find files in the home directory that can be written by other users

[root@localhost] # find ~-perm-002/root/num [root@localhost ~] # find ~-perm-002-exec chmod Omurw {}\; [root@localhost ~] # ll num--w--w---- 1 root root 35 Jan 21 05:55 num

Example 4: find all files belonging to the / var directory whose master is root and the group is mail

[root@localhost] # find / var-user root-group mail-ls # default relationship is with 1179652 4 drwxrwxr-x 2 root mail 4096 Jan 23 11:04 / var/spool/mail

Example 5: find all the files in the / var directory that do not belong to root, lp or gdm

[root@localhost ~] # find / var!-user root!-user lp!-user gdm

Example 6: find files whose contents have been modified in the last week in the / var directory, and the owner is neither root nor postfix.

[root@localhost ~] # find / var/-mtime-7!-user root!-user postfix-ls1179676 4 drwx- 3 daemon daemon 4096 Jan 23 11:04 / var/spool/at524399 4 drwx- 2 nginx nginx 4096 Jan 23 03:16 / var/log/nginx524413 0-rw-r--r-- 1 nginx root 0 Jan 23 03:16 / var/log/nginx/ Access.log524391 0-rw-r--r-- 1 nginx root 0 Jan 21 03:44 / var/log/nginx/error.log132174 4 drwx- 3 nginx nginx 4096 Jan 21 03:44 / var/lib/nginx132175 4 drwx- 7 nginx nginx 4096 Jan 21 03:44 / var/lib/nginx/tmp132173 4 drwx- 2 nginx root 4096 Jan 21 03:44 / var/lib/nginx/tmp/client_body132219 4 drwx- 2 nginx root 4096 Jan 21 03:44 / var/lib/nginx/tmp/proxy132221 4 drwx- 2 nginx root 4096 Jan 21 03:44 / var/lib/nginx/tmp/uwsgi132222 4 drwx- 2 nginx root 4096 Jan 21 03:44 / var/lib/nginx/tmp/scgi132220 4 Drwx- 2 nginx root 4096 Jan 21 03:44 / var/lib/nginx/tmp/fastcgi

Example 7: find files that have no owners or groups on the current system and have been accessed in the most recent week

[root@bash] # find /-nouser-o-nogroup-a-atime-7

Example 8: find all files in the / etc directory that are larger than 1m and whose types are ordinary files

[root@bash] # find / etc/-size + 1m-type f/etc/selinux/targeted/policy/policy.29/etc/udev/hwdb.bin

Example 9: find files in the / etc directory where all users do not have write permission

[root@bash ~] # find / etc/!-perm / 222/etc/pki/ca-trust/extracted/java/cacerts/etc/pki/ca-trust/extracted/openssl/ca-bundle.trust.crt/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem/etc/pki/ca-trust/extracted/pem/email-ca-bundle.pem/etc/pki/ca-trust/extracted/pem/objsign-ca-bundle.pem/etc/lvm/profile/cache -mq.profile/etc/lvm/profile/cache-smq.profile/etc/lvm/profile/command_profile_template.profile/etc/lvm/profile/metadata_profile_template.profile/etc/lvm/profile/thin-generic.profile/etc/lvm/profile/thin-performance.profile/etc/openldap/certs/password/etc/gshadow/etc/dbus-1/system.d/cups.conf/etc/shadow/etc/gshadow-/etc/ld.so.conf.d/kernel-3.10. 0-327.el7.x86_64.conf/etc/shadow-/etc/udev/hwdb.bin/etc/machine-id/etc/pam.d/cups/etc/sudoers

Example 10: find files with at least one class of users in the / etc directory that do not have execute permissions

[root@bash] # find / etc/!-perm-111l # at least one category of users does not have, that is, none of them

Example 11 VRV. Find files under the / etc/init.d directory where all users have execute permissions and other users have write permissions

[root@bash] # find / etc/init.d-perm-113/etc/init.d

Or

[root@bash] # find / etc/init.d-perm-111111-perm-002/etc/init.d

Example 12: Morgan's law finds files in the / tmp directory where the owner is not root and the file name does not start with f

[root@centos7 ~] # find / tmp\ (- not-user root-a-not-name 'favored'\)-ls

That is,

[root@centos7 ~] # find / tmp-not\ (- user root-o-name 'fags'\)-ls

Example 13: find all files with the .conf suffix under / etc/ except the / etc/sane.d directory

[root@bash ~] # find / etc-path'/ etc/sane.d'-prune-o-name'* .conf'

Example 14: match file path or file

[root@bash ~] # find / usr/-path'* local'/usr/bin/abrt-action-analyze-ccpp-local/usr/share/doc/postfix-2.10.1/examples/qmail-local/usr/share/aclocal/usr/libexec/postfix/local/usr/local

Example 15: matching file paths based on regular expressions

[root@bash] # find. -regex ". * txt$". /. Mozilla/firefox/4dqu966q.default/revocations.txt./vimrc/spf13-vim/LICENSE.txt./a.txt Thank you for your reading! This is the end of this article on "how to query files in linux". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it out for more people to see!

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