Linux Base File Lookup

File Lookup

Find eligible files on the file system;

Implementation tools: Locate, find

Locate

Rely on the pre-built index library;

Automatic implementation of the system (periodic tasks);

Manually update the database (UPDATEDB);

Operating characteristics:

Fast search speed;

Fuzzy search;

Non-real-time lookup;

Locate [OPTION] ... PATTERN ...

-B: Matches only the base name in the path;

C: Statistics of the total number of eligible documents;

-r:bre (based on basic regular expressions)

Note: The index build process needs to traverse the entire root filesystem, consuming resources extremely;

Find

Real-time Lookup tool to complete file search by traversing the file system hierarchy under the specified starting path;

Operating characteristics:

The search speed is slightly slower;

Accurate search;

Real-time search;

Usage:

Find [OPTIONS] [Find starting path] [find condition] [processing action]

Find the starting path: Specify a specific search target starting path, default to the current directory;

Find criteria: The specified lookup criteria can be based on file name, size, type, affiliation, permissions, and so on, the default is to find all the files under the specified path;

Handling actions: Actions that are made on files that match the search criteria, such as deletions, which are output to standard output by default;

Search criteria:

Expressions: Options and tests

Test: The result is usually a Boolean ("true", "false")

Search by file name:

-name "pattern"

-iname "pattern"

supports GLOB-style wildcard characters;

*, ?, [], [^]

-regex pattern: Finds a file based on a regular expression pattern, which matches the entire path, not its name;

Find based on file affiliation:

-user USERNAME: Find all files belonging to the owner of the specified user;

-group GRPNAME: Finds all files belonging to the specified group of groups;

-uid uid: Finds all files that belong to the UID specified by the master;

-gid GID: Finds all files belonging to the specified GID of the group;

-nouser: Find files that are not owned by the master;

-nogroup: Find files without a group;

Find by File type:

-type Type:

F: Normal file

D: Catalog file

L: Symbolic Link file

B: Block device files

C: Character device file

P: Pipeline File

S: Socket file

Combination test:

With:-A, default combination logic;

Or:-O, as long as one of the two is compatible

Non:-not,!

Practice:

1, find out the/tmp directory subordinate to the main non-root all files;

2. Find the file name in the/tmp directory that does not contain the fstab string;

3, find out the/tmp directory subordinate Master is non-root, and the file name does not contain fstab string files;

    ! A-a! B =! (A-o B)

! A-o! B =! (A-a B)

Find by File Size:

-size [+|-] #UNIT

Common units: K, M, G default byte

#UNIT: (#-1, #)

-#UNIT: [0,#-1]

+ #UNIT: (#, OO)

Find by Time stamp:

In "Days" as the unit:

-atime [+|-]#

#:[#, #-1)

-#: (#, 0]

+#: (Oo, #-1)

-mtime

-ctime

In "Minutes" units:

-amin

-mmin

-cmin

Search by permissions:

-perm [/|-]mode

Mode: precise permission matching;

/mode: Any one (r,w,x) of the permissions of any class of users (U,g,o) is satisfied with the condition;

There is a "or" relationship between 9-bit permissions;

-mode: Each class of users (U,g,o) in the permissions of each bit (r,w,x) at the same time meet the condition is satisfied;

There is a "and" relationship between 9-bit permissions;

Handling actions:

-print: Output to standard output, default action;

-ls: Similar to the "ls-l" command for the found file, the output file details;

-delete: Delete the found file;

-fls/path/to/somefile: Saves the long format information of all files found to the specified file;

-ok COMMAND {} \; : Executes commands for each file that is found, and each operation is confirmed by the user;

-exec COMMAND {} \; : Executes commands for each file that is found;

Note: Find passes the file path found to the following command, it is first to find out all eligible file paths, and one-time pass to the following command;

However, some commands cannot accept too long arguments, at which point the command execution fails, and another way to circumvent this problem:

Find | Xargs COMMAND

Homework: Learn the use of XARGS commands;

Practice:

1. Find the main root of the/var directory, and belong to all files or directories of mail;

~]# find/var-user root-a-group mail-ls

2. Find all files or directories that do not belong to root, bin or hadoop under the/usr directory; in two ways;

~]# find/usr-not-user root-a-not-user bin-a-not-user Hadoop

~]# find/usr-not \ (-user root-o-user bin-o-user hadoop \)-ls

3, find in/etc directory in the last week of its content has been modified, and the owner is not the root user is not a Hadoop user files or directories;

~]# find/etc-mtime-7-a-not \ (-user root-o-user hadoop \)-ls

~]# find/etc-mtime-7-a-not-user root-a-not-user hadoop-ls

4. Find files or directories that are not in or belong to the current system and have been visited in the last week;

~]# Find/\ (-nouser-o-nogroup \)-atime-7-ls

5. Find all files that are larger than 1M and type ordinary files in/etc directory;

~]# find/etc-size +1m-type f-exec ls-lh {} \;

6, look for all the users in/etc directory do not have permission to write files;

~]# Find/etc-not-perm/222-type F-ls

7, Find/etc directory at least one class of users do not have permission to execute files;

~]# Find/etc-not-perm-111-type F-ls

8, find/etc/init.d/directory, all users have execute permission, and other users have write permission to all files;

~]# Find/etc-perm-113-type F-ls

Blog assignments: Find details

Linux Base File Lookup