File locating and locating in Linux system

File Lookup in Linux systems

Keyword File Finder | Find | Locate

This article mainly describes the file lookup of the two commands--find and locate, as well as the compressed packaging commands--compress, GZIP,BZIP2,XZ and so on. Questions or suggestions can be sent to email [email protected]

Locate

The locate command is by querying a pre-built file index database on a Linux system, which, to be exact, is the default location of the database/var/lib/mlocate/ Mlocate.db, this database is usually updated periodically by the system, but can also be manually updated by the UpdateDB command, but it may take a long time period, especially if the file system occupancy rate is high.

Features of the Locate command lookup:

查找速度快模糊查找非实时查找

command format and common options:

locate [OPTION]... PATTERN...        -h, --help      查看帮助文档          -i              忽略大小写搜索    -n  N           最多显示N个匹配项目 -r, --regexp 支持进行基本正则表达式匹配，默认支持glob统配符 --regex 支持使用扩展正则表达式 -c 统计搜索到匹配的条目，但不输出具体条目

Find command

Find command Lookup has the following characteristics relative to the locate command

查询速度较快精确查找实时查找

Grammar:

[-H] [-L] [-P] [-D  debugopts] [-Olevel] [path...][expression][-H] [-L] [-P] 三选项用来控制处理符号链接文件[-D] 控制dubug[-O] 查询，设置优化等级

The above 5 parameters are basically not used, if needed, the location must be before the path [path]

[OPTION]... [查找路径] [查找条件] [处理动作]

Find a path: Specify the directory you want to find, and if it is the current directory, use "." Replace

Find criteria: Specify the lookup criteria, which can be file name, size, permissions, etc.

Handling actions: Working with eligible files, default output to screen

The following details the search criteria:

Search by file name

-name,      直接查找文件名，支持glob风格查找-iname,     不区分大小写，支持glob风格查找-regex,     支持正则表达式查找文件名-iregex,    不区分大小写，支持正则表达式查找文件名注意：如果对glob不了解，可以用man 7 glob查看

Find based on file dependencies

-user,   根据属主查找-group,     根据属组查找-uid        根据属主id查找-gid        根据属组id查找-nouser 判断是否属于无属主文件-nogroup 判断是否属于无属组文件

Find by File type

-type

Common file types are

f    普通文件d       目录文件l       符号链接文件b       块文件c       字符设备文件p   管道文件s   套接字文件

Find by File size

-size[+|-]  UNIT常用单位：k, M, G

Find by timestamp

以“天”为单位：-atime[+|-]-mtime-ctime以“分钟”为单位：-amin-mmin-cmin

Find based on permissions

modemode: 精确权限匹配-mode/mode: 任何一类用户的权限满足即可+mode: 已废弃这种用法

Handling actions

-print  输出至标准输出，默认的动作-ls 类似于对查找的文件执行"ls -l"命令，输出文件的详细信息-delete 删除查找到的文件-fls file 把查找到的所有文件的长格式信息保存到指定文件-ok CMD {} \; 执行CMD,执行前询问-exec CMD {} \; 执行CMD

Combination Test

The default between each condition is to connect with, and if you need to use another combination test, you must add

-a      与-o      或-not, !    非

De Morgan Law

(非 P) 或 (非 Q) = 非(P 且 Q)(非 P) 且 (非 Q) = 非(P 或 Q)

Practice

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

# find /var -user root -group mail

2. Find all files or directories that do not belong to root, LP, or GDM in the/usr directory;

# find /usr -not -user root -a -not -user lp -a -not -user gdm# find /usr -not \( -user root -o -user lp -o -user gdm \)

3, Find/etc directory in the most Monday weeks of its content has been modified, and is not the root of the master, nor is it postfix files or directories;

# find /etc -mtime -7 -a -not -user root -a -not -user postfix# find /etc/ -mtime -7 -a -not \( -user root -o -user postfix \)

4. Find files or directories on the current system that are not owned by the master or group and have been visited in the last week;

# find / \( -nouser -o -nogroup \) -a -atime -7# find / \( -atime -7 -nouser -o -nogroup \) -ls

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

# find /etc -size +1M -type f

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

find /etc -not -perm 222 -type f -ls

File locating and locating in Linux system