File lookup commands under Linux

File lookup: Search for files by filename or file property;

A) Locate

Fuzzy Lookup:
Based on a dedicated database to find, the database should be created in advance, and regularly updated;
You can manually update the locate database using the UpdateDB command;
Find very fast, find accurate to very limited;

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II) find

Exact search:
The search precision is high, the speed is slightly slow;
A traversal scan of a filename or file property at the specified location; It is strongly not recommended to find the root directory;
Real-time search;
Use the Find command to search only the directory where the current user has read and execute permissions;

Find command:
Find-search for files in a directory hierarchy
Find [OPTIONS ...] [Find Path] [Search Criteria] [Handling Action]
Find path: Default to the current working directory, you can specify a specific directory path;
Search criteria: The criteria for the searches can be file name, file size, file type, file permissions, etc.; By default, all files in the specified directory;
Handling actions: Perform a processing operation on a file that matches the criteria, and output the lookup results to the display by default;

Search by file name:
-name file name, support for using globbing, (*,?, [], [^])
-iname file name, ignoring letter case, support using globbing, (*,?, [], [^])

Search by inode number of the file:
-inum inode Number: Find the corresponding file name and path by the given inode number;
-samefile name: Finds the corresponding inode number by the given file name, and then determines all filenames and paths with that inode number;
-links N: Finds all files with the number of links n;

Find by Regular expression:
-regex pattern: Matches the entire file path string with pattern, not just the name of the given file;

Search according to the file's owner and owner group:
-user uname: Search According to the user name of the owner for the specified user
-uid UID: Search by Owner for a UID
-group Gname:
-gid GID:

-nogroup: There is no group name on the genus Group of the file;
-nouser: The owner of the document has no user name;

Find by File type:
-type file Type: "
B: Block device
C: Character device
D: Catalog file
F: Normal file
L: Symbolic Link file
P: Pipeline File
S: Socket file
-xtype file type: The matching of the symbolic link file needs to be matched with other options;

To find based on a timestamp:
In days:
-atime [+|-]n: Find based on access time
-ctime [+|-]n: Search by change time
-mtime [+|-]n: Find based on modified time
N:[N,N+1)
+n:[n+1,+∞)
-n:[now,n)
In minutes:
-amin [+|-]n
-cmin [+|-]n
-mmin [+|-]n

Example:
5-28-11-18
-mtime-3
5-25-11-18
-mtime 3
5-24-11-18
-mtime +3

To find the file size:
-size [+|-]N[CWBKMG]
N: (N-1,n]
-N:[0,N-1]
+n: (n,+∞)

Example:
Find-size +2k
All files larger than 2KB in the current directory;
find-size 2k
Files between all 1kb-2kb in the current directory;
find-size-2k
All files less than 1KB in the current directory;

Combination conditions:
-A: Logical AND, default can be omitted;
-O: Logical OR
-not,!: Logical Non-

The logic combination condition follows the Demogan law:
Non-(A and b) = = = Non-A or non-B
Non-(A or b) = = = Non-A and non-B

Search by permissions:
-perm [/|-]mode
Mode: Exact Match of specified permissions
/mode: The implied logic or the relationship, any one permission bit of permission to have a permission to match, can satisfy the condition;
-mode: The implied logic and the relationship, each permission bit permission must contain the specified permission bit, in order to satisfy the condition;

All have to take back any one No
! (A and B and c) =!a or!b or!c
All are not taken against any one that has
! (!a and!b and!c) = A or B or C

Handling actions:
-print: Output to the display screen, the default action;
-ls: Performs Ls-li command display on the results that are found;
-exec COMMAND {} \;:
-ok COMMAND {} \;:
Execute command for the found results;
Difference:
-exec is non-interactive;
The-ok is interactive;
{}: Placeholder used to refer to the path information of all files found by the Find command;

-exec and-ok to perform operations:
chmod a-r $ (find-perm-444-type f)
Find-perm-444-type F | Xargs chmod a-r

Note: Pipelines convey pure string information, so if the command after the pipeline is not a command to process the string, you need to use the Xargs command to convert it to a parameter that can be processed by the following command;

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Give some chestnuts:

Check all the normal files in the current directory
# Find. -type f-exec ls-l {} \;
-rw-r–r–1 root root 34928 2003-02-25./conf/httpd.conf
-rw-r–r–1 root root 12959 2003-02-25./conf/magic
-rw-r–r–1 root root 2003-02-25./conf.d/readme
Check all the normal files in the current directory and use the LS-L command in the-e x E C option to list them

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In the/Logs directory, look for files that change time before 5th and delete them:
$ find Logs-type f-mtime +5-exec-ok rm {} \;

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Query for files modified on the day
]# Find/-mtime-1-type f-exec ls-l {} \;


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Query and give it to awk to handle it.
]# who | awk ' {print ' \ t '
CNSCN pts/0

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Awk-grep-sed

]# Df-k |   awk ' {print '} ' |   Grep-v ' None ' | sed S "/\/dev\///g"
File system
Sda2
Sda1
]# Df-k |   awk ' {print '} ' | Grep-v ' None '
File system
/dev/sda2
/dev/sda1
1) Find all the *.h in/tmp and look for "syscall_vector" in these files, and finally print out all the filenames that contain "syscall_vector"

A) find/tmp-name "*.h" | Xargs-n50 grep syscall_vector
B) grep syscall_vector/tmp/*.h | Cut-d ': '-f1| Uniq > FileName
C) find/tmp-name "*.h"-exec grep "Syscall_vector" {} \; -print

2) Find/-name filename-exec rm-rf {} \;
Find/-name filename-ok rm-rf {} \;

3) For example, to find files larger than 3M on the disk:
Find. -size +3000k-exec ls-ld {};

This article from "Fuboyuan" blog, declined reprint!

File lookup commands under Linux