1.9 linux base (nine) - File Finder find

1.9 linux base (nine) - File Finder find

1.9.1 File Finder

• Finding qualified files on the file system
• File Find: locate, find
• Find a non-real time (a database lookup): locate
  
• Real-time look: find

1.9.2 locate

• The query system pre-built index file database
  
• /var/lib/mlocate/mlocate.db depends on the index built in advance
• The index is constructed when the system is relatively idle automatic (periodic task), the administrator manually update the database (updatedb)
• Index building process needs to traverse the entire root file system, extreme consumption of resources
• Work characteristics:
  • Find Fast
  • Fuzzy Lookup
  • Find a non-real time
    
  • Search is a full path to the file, not just the file name
    
  • You may only search for a user with read and execute permissions to the directory
• locate command
• locate KEYWORD
• Common options
  • -i case-insensitive search
  • N -n include only matches the first N
  • -r using regular expressions
• File name or path in search examples with "conf" of
  • locate conf
• Use Regex to search for files with ".conf" at the end of
  • locate -r ‘.conf$’

1.9.3 find

• Real-Time Finder, to complete the path to the file specified by traversing Find
• Work characteristics:
  • Find a bit slower
  • Exact Match
  • Find real-time
    
  • You may only search for a user with read and execute permissions to the directory
• find syntax: find [OPTION] ... [to find the path] [search criteria] [processing operation]
  • Search Path: Specifies the specific target path; defaults to the current directory
  • Search Terms: specified search criteria can be standard file name, size, type, permissions, and so on; the default is to find all the files in the specified path
    
  • Actions: do operations that meet the conditions file, the default output to the screen

1.9.3.1 search criteria

• It refers to the hierarchical search
  • -maxdepth level maximum depth search directory, specify the directory to Level 1
    
  • -mindepth level minimum depth search directory
• According to the file name and inode lookup:
  • -name "file name": supports glob *,, [], [^]?
    
  • -iname "File Name": not case sensitive
    
  • -inum n Find -samefile name by the same inode number inode number of the file
    
  • -links n n number of links to files
    
  • -regex "PATTERN": PATTERN to match the entire file path string, not just the file name
• According to owner, is a set of lookup:
  • -user USERNAME: Find owner for the specified user (UID) file
  • -group GRPNAME: Find is a group for the specified group (GID) file
  • -uid UserID: Find owner's UID number for the specified file
    
  • -gid GroupID: Find GID is a group for the specified number of files
    
  • -nouser: Find the file is not owner of
    

  • -nogroup: Find the file does not belong to the group

    1.9.3.2 depending on the file type to find:

• -type TYPE:
  • f: regular file
    
  • d: directory file
  • l: symbolic link file
  • s: socket file
  • b: block device file
  • c: character device file
  • p: pipe file
  • Empty file or directory
    

  • -empty find /app -type d -empty

    1.9.3.3 combination of conditions

• A combination of conditions:
  • And: -a
    
  • Or: -o
    
  • Non-: -not,!
    
• De Morgan's Law:
  • (Non-A) or (non-B) = non (A and B)
    
  • (Non-A) and (non-B) = non (A or B)
    
  • Example:! A -a B = (A -o B)!!
    
  • !A -o !B = !(A -a B)
• find examples
• find -name snow.png
• find -iname snow.png
• find / -name “*.txt”
• find /var –name “*log*”
• find -user joe -group joe find -user joe -not -group joe
• find -user joe -o -user jane
• find -not ( -user joe -o -user jane )
• find / -user joe -o -uid 500

find examples

• Find out the / tmp directory, the owner is not root, and the file name does not begin with 'f' file
  • find /tmp ( -not -user root -a -not -name 'f*' ) -ls
  • find /tmp -not ( -user root -o -name 'f*' ) –ls
• Excluding directories Example:
  • Find / etc / down, in addition to all other .conf file suffix /etc/sane.d directory of
    
  • find /etc -path ‘/etc/sane.d’ -a –prune -o -name “*.conf”
    
  • Find / etc / down, all .conf suffix /etc/sane.d and / etc / fonts directory of files other two
    
  • find /etc (–path ‘/etc/sane.d’ –o –path ’/etc/fonts’ ) -a -prune –o -name “*.conf”

1.9.3.4 based on file size to find:

• -size [+|-]#UNIT
  • Common units: k, M, G, c (byte)
    

  • UNIT: (# -1, #] as: 6k represents (5k, 6k]

  • - # UNIT: [0, # - 1] as: -6k represents [0,5k]
    
  • + # UNIT: (#, ∞) such as: + 6k represents (6k, ∞)

1.9.3.5 According to the time stamp

• "Day" as a unit;
  • -atime [+|-]#,
    

  • : [#,#+1)

  • +#: [#+1,∞]
    
  • -#: [0,#)
    
  • -mtime
    
  • -ctime
    
• To "minutes" for the unit:
  • -amin
    
  • -mmin
    
  • -cmin

1.9.3.6 look under the authority

• -perm [/|-]MODE
  • MODE: exact permissions match
    
  • / MODE: any class rights (u, g, o) as long as an object can be matched, or relationship, centos7 start out from the +
    
  • -MODE: each type of object must have a designated authority, and relations
    
  • 0 indicates no concern
  • find -perm 755 matches permission mode exactly 755 files
  • Whenever any person has write permissions, find -perm +222'll match
  • Only when everyone has write permissions, find -perm -222 will match
  • Only when other people (other) have write access, find -perm -002 will match

1.9.3.7 processing operation

• -print: default processing operation, display to the screen -
• -ls: Performs like "ls -l" command to find files
• -delete: Delete files found
• -fls file: save the long form information to find all the files to the specified file
• -ok COMMAND {}; find each file specified by a COMMAND execution command, for each file before executing the command will require the user to confirm the interactive
• -exec COMMAND {} \; each of the found file designated by the execution command COMMAND
• {}: Look for references to the file name itself
• When find to find the files delivered to the specified after the command, find command all eligible to file a one-time transfer back
  

如：find / -name zhu.sh -exec rm {} \\; 容易误删除  
如：find / -name zhush -ok rm {} \\;
[root@centos77 ~]# find / -name a -ok rm {} \;
< rm ... /root/a > ? n
< rm ... /var/lib/yum/yumdb/a > ? n
< rm ... /usr/share/terminfo/a > ? n

1.9.3.8 parameter substitution xargs

• Since many command does not support pipeline | to pass parameters, and daily work there is need, so there xargs command
• Xargs parameters for generating a command, data can be read stdin xargs, and a space character or a carriage return arguments become separated data stdin
  
• Note: The file name contains a space character within the meaning of the noun or other circumstances
• Some commands can not accept too many parameters, the command may fail, xargs can be resolved
• Example: ls f * | xargs rm find / sbin -perm +700 | ls -l command is wrong find / sbin -perm +7000 | xargs ls -l
• find and xargs format: find [option] ..... [search path] [search criteria] [processing operation] | xargs COMMAND will find as xargs cmd argument
  

[root@centos77 ~]# find / -name a |xargs rm   不会进行交互，且忽略别名会直接删除；
find / -type f -name "*.conf"|xargs grep -n '80'

1.9.3.9 find examples

• Backup configuration file, add this extension .orig
  
• find -name “*.conf” -exec cp {} {}.orig ;
• Tip delete temporary files for more than 3 days in the presence of joe
  
• find /tmp -ctime +3 -user joe -ok rm {} ;
• Looking file can be written by other users in the home directory
  
• find ~ -perm -002 -exec chmod o-w {} ;
• Find privileges under the data / 644, as an ordinary file suffix sh, adding execute permissions
  
• find /data –type f -perm 644 -name “*.sh” –exec chmod 755 {} ;
• View / home directory find / home -type d -ls

1.9.3.10 practice questions:

1. Find all the file / var / directory under the main root and belongs to a group mail

find /var -user root -a -group mail 

2, Find / does not belong to all the files root, bin or under the usr directory hadoop

find /usr -nouser root -a -nouser bin -a -nouser hadoop

3, look in / etc / directory last week revised its content and does not belong and do not belong to the root file hadoop

find /etc/ -mtime -7-a -not -user root -a -not -user hadoop

4, find the file currently no owner, or belong to groups on the system, and within a month had been recently visited;

find  / \(-nouser -o -nogroup\) a  -atime  -30 

5, find / etc 1M and all files larger than an ordinary type of file / directory;

find /etc/ -size +1M -a -type f （这里不能加-f）

6. Find / etc / directory of all users do not have write permission

find /etc/ -not -perm +222

7. Find / etc / directory of all users have write access to the file

find /etc/  -perm -222

8. Find / etc / directory with at least one type of user does not have write permission

find /etc/ -not -perm -222

At least look at / etc / directory of a class of users have write access

find /etc/  -perm  +222

9. Find /etc/init.d directory and all users have execute permissions to other users with write access to the file

find /etc/init.d -perm -113