Linux file Lookup Command which detailed

A file doesn't know where it is, and you can usually use some of the following commands to find:
Which view the location of the executable file
Whereis View the location of the file
Locate view file location with database
Find actual search hard disk query file name
Attached: Linux file Lookup command find detailed

which command detailed

The which command works by searching for the location of a system command in the path specified by the path variable and returning the first search result. That is, by using the which command, you can see whether a system command exists, and which location is executing the command.
1. Command format:

which executable file name

2. Command function:

The which directive searches for the location of a system command in the path specified by the path variable and returns the first search result.
3. Command parameters:
-n Specifies the filename length, which must be greater than or equal to the longest file name in all files.
-P is the same as the-n parameter, but the path to the file is included here.
-W Specifies the width of the field when output.
-V Display version information
4. Use instance:

Example 1: Finding a file, displaying a command path

Command:

Which lsmod

Output:

[Root@localhost ~]# which PHP
/usr/local/php/bin/php

[Root@localhost ~]# which PWD
/bin/pwd

Description

Which is based on the directory in the PATH variable configured by the user to search for a running file! Therefore, the commands found in the different PATH configuration contents are certainly not the same!

Example 2: Use which to find which

Command:

which which

Output:

[Root@localhost ~]# which which

Alias Which= ' Alias | /usr/bin/which--tty-only--read-alias--show-dot--show-tilde '

/usr/bin/which

Description

There will be two which, one of which is alias. This is called "command alias", which means that the input which will wait for the following sequence of commands!

Example 3: Find the CD command
Command:

which CD

Output:

Description
CD this common command can not find Ah! Why, then? This is because the CD is a built-in command for bash! But which default is to find the PATH within the specification of the directory, so of course, can not find Oh!