One Linux command per day (1): Which command

We often find a file in Linux, but do not know where to put it, you can use some of the following commands to search:

Which view the location of the executable file.
Whereis View the location of the file.
Locate to view the file location with the database.
Find actual search hard disk query file name.

The purpose of the which command is to search for the location of a system command in the path specified by the path variable, and return the first search result. That is, with the which command, you can see whether a system command exists, and the command that executes exactly which location.

1. Command format:

which executable file name

2. Command function:

The which instruction 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 length of the file name, 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 at the output.

-V Display version information

4. Usage examples:

Example 1: Finding files, displaying command paths

Command:

Which lsmod

Output:

[email protected] ~]# which PWD

/bin/pwd

[email protected] ~]# which adduser

/usr/sbin/adduser

[Email protected] ~]#

Description

Which is to search for a running file based on the directory within the PATH variable configured by the user! Therefore, the different PATH configuration content found the command of course not the same!

Example 2: Use which to find which

Command:

which which

Output:

[email protected] ~]# which which

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

/usr/bin/which

[Email protected] ~]#

Description

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

Example 3: Find the CD command

Command:

which CD

Output:

Description

CD is a common command can not find Ah! Why is it? This is because the CD is a command built in bash! But which default is to find the PATH within the standard directory, so of course, must not find!

One Linux command per day (1): Which command (GO)