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Find Which command for script files

The which command searches for the location of a system command in the path specified by the PATH variable and returns the first search result. In other words, using which command, you can see whether a system command exists and where the command is executed.

syntax: which [-a] command

-a: List all commands found in path directory

Examples:

which ifconfig

which which #Find out which file name

File search whereis

The whereis command can only be used to search for program names, and returns all information if parameters are omitted.

Syntax: whereis [-bmsu] file or directory name

-l : can list several main directories whereis will query

-b: only binary format files

-m: only find files under manual path of description file

-s: Find only source files

-u: Find other special files that are not in the above three projects

Examples:

whereis ifconfig #Find ifconfig file name

whereis -m passwd #only files in man are displayed

find command

find, used to find files in the file tree and process them accordingly

-name: Find files by file name

-perm: Find files by file permissions

-user: Find files by file owner

-size: Find files according to the specified file size [+n: greater than, -n: less than, n: equal]

-group: Find files by the group to which they belong

-mtime: Find files by file change time, -n means within n days,+n means n days ago

-newer file1 file2: Find files changed between file1 and file2

Examples:

find / -name xitai #Find system-wide file named xitai

find -mtime -2 #Find files modified in 48 hours

find /usr/local -size +100M #Find files larger than 100M

find -type d |sort #Find and sort all current target directories

find /usr/local/apache-tomcat-admin/ -perm 755 #Find files with permissions 755 in the specified directory

find /etc/ -newer /etc/passwd #Find files that are newer than/etc/passwd

locate command

The locate command is actually another way to write "find -name," but it is much faster because it does not search a specific directory, but a database (/var/lib/locatedb) that contains all the local file information. Linux automatically creates this database and updates it every day, so you can't find the latest files that have changed using the locate command. To avoid this, manually update the database using the updatedb command before using locate.

updatedb: Create the locate database before the first run

Parameters:

-i: ignore case

-c: Do not output file name, only count file number

-l : Output only a few lines

-r: followed by regular expressions

-S: Output database file related information

Examples:

locate -l 5 passwd

If it is wrong:

first install

yum -y install mlocate

Another error:

initialization

updatedb

locate -l 5 passwd

locate -S

type

The type command isn't really a lookup command; it's used to distinguish whether a command comes with the shell or is provided by a separate binary file external to the shell. If a command is external, using the-p argument displays the path to the command, equivalent to which command.

Examples:

type -p ifconfig

grep

Used to filter/search specified strings. Regular expressions can be used and can be used with a variety of commands.

Usage: grep [Options] Find content source file

-A: Display the line that matches and what follows

-B: Display the line that matches and what precedes it.

-C: Display the matching row and the content before and after

-c: Calculate the number of rows that match

-n: Display matching rows and row numbers

-i: ignore case

regular expression

^:'^grep' matches all lines starting with grep

'matches all rows ending in grep

.：'gr.p' means match 'gr' followed by any character followed by 'p'

:'grep' indicates a line matching one or more spaces followed by grep

[]:[Gg]rep means matching Grep and grep

[^]:[^A-FH-Z]rep indicates matching lines that do not begin with A-F, H-Z and follow rep

Examples:

grep -n 'cc' aa.txt

grep -in 'DD' aa.txt

grep -vn 'cc' aa.txt

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