The difference between the Which,whereis,locate,find commands under Linux

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.

1.which

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.

1.1. Command format:

which executable file name

1.2. 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.

1.3. 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

1.4. Usage examples:

Example 1: Finding files, displaying command paths

which pwd/bin/pwd[[email protected]whichpasswd/usr/bin/passwd [email protected]which  java/home/bigdata/software/java/bin/java

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

[Email protected] ~]$ which whichalias 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 the "command alias", meaning that the input which will wait for the next sequence of commands!

Example 3: Find the CD command

[Email protected] ~]$ which CD inch (/home/bigdata/software/java/bin:/usr/lib64/qt-3.3/bin:/home/bigdata/software/spark-1.5. 2.2-bin-2.4. 0.7/bin:/home/bigdata/software/r-3.2. 1/bin:/home/bigdata/software/anaconda/bin:/home/bigdata/software/java/bin:/home/bigdata/software/ hadoop/bin:/home/bigdata/software/hive/bin:/home/bigdata/software/sqoop/bin:/home/bigdata/software/hbase/bin:/ home/bigdata/software/zeppelin/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/bigdata/ Software/hadoop/bin:/home/bigdata/software/hive/bin:/home/bigdata/software/sqoop/bin:/home/finance/bin)

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!

2.whereis

The Whereis lookup is very fast compared to find, because the Linux system records all the files in the system in a database file, and when you use Whereis and the locate described below, the data is looked up from the database. Instead of looking through the hard drive like the Find command, the efficiency will naturally be high.

However, the database file is not updated in real time and is updated once a week by default, so when we use Whereis and locate to find files, we sometimes find data that has been deleted, or just created the file, but cannot find it because the database file is not updated.

2.1. Command format:

Whereis [-BMSU] [BMS directory name-f] File name

2.2. Command function:

The Whereis command locates the location of the executable file, the source code file, and the Help file in the file system. The properties of these files should belong to the original code, binary files, or Help files. The Whereis program also has the ability to search for source code, specify alternate search paths, and search for unusual items.

2.3. Command parameters:

-B locates the executable file.

-M locate the help file.

-S Locate the source code file.

-U searches the default path for files other than executables, source code files, and Help files.

-b Specifies the path to the search executable file.

-m specifies the path to the search Help file.

-s Specifies the path of the search source code file.

2.4. Usage examples:

Example 1: Find files related to * * files

Whereis/usr/bin/java/etc/java/usr/lib/java/usr/share/java/usr/share/man/man1/java. 1 . Gz[[email protected]whereis/usr/bin/svn/usr/share/man/man1/svn. 1 . Gz[[email protected]whereis  tomcattomcat:

Tomcat is not installed, can not find out, SVN installation found a lot of related files

Example 2: Only binary files are found

Whereis -/usr/bin/svn[[email protected]whereis -/usr/share/man /MAN1/SVN. 1 . Gz[[email protected]whereis -s SVNSVN:

Whereis-m SVN to find the description document path, Whereis-s svn for source files.

The difference between the Which,whereis,locate,find commands under Linux