What you could find out asking which, whereis and whatis in Linux

By | August 13, 2021

The which, whereis and whatis instructions on a Linux system present details about instructions. They supply associated however not an identical info. On this submit, we’ll try the variations and supply a script for getting info that’s out there from all three instructions. We’ll additionally discover some pattern instructions for taking a look at secondary (i.e., not part 1) man pages.

The which command will present you the file-system location for a command’s executable. That is the file that’s learn and run everytime you kind the command title.

The which command can even report in your aliases and present you the instructions they invoke.

Like which, the whereis command will present you the file=system location for the executable related to a command, however it should additionally inform you the place the man (handbook) pages are situated.

Within the instance beneath, there are two or three man pages for every of the instructions.

The whatis command gives transient descriptions of instructions. Every description is related to one of many man pages for that command as proven within the instance beneath.

To view the first man web page for any command, simply kind “man” plus the title of the command, for instance, “man date”. Add the person web page part (e.g., “man 3p shutdown”) for a unique man web page part. Observe that on the prime of the person web page you will notice a affirmation of the command and the actual man web page part:



(The output above has been truncated.)

Man pages are organized into as many as 9 sections:

You possibly can run all three of the which, whereis and whatis instructions any time you wish to know just a little extra in regards to the instructions you’re operating and the place they’re saved in your system. In the event you run a command and get an surprising response, trying out what executable you’re coping with might be essential.

Hmm! One thing’s just a bit off in that instance. Whilst you’re impossible to get a response like that proven, it’s doable to have two executables on a system with the identical title. On this case, which one you find yourself operating will a minimum of partially rely in your search path. Your private bin listing ought to in all probability not be sitting within the first place in your $PATH variable nor ought to “.” (present place) due to the danger of operating a command aside from what you supposed.

The script beneath will run all three instructions and show the output in a helpful format. The truth is, it might probably settle for an inventory of instructions and show the command output for wanting into every of them.

Right here’s an instance of operating the script for 2 instructions:

The the place, whereis and whatis instructions present helpful summaries of instructions, exhibiting the place the executables are situated and pointing to the related man pages. The which command may confirm which executable you might be utilizing while you kind a command title.

Seek the advice of the person pages to find out about all of the choices out there and get a extra full clarification of how these instructions work.