Common problem for system administrators or daily Linux users is command not found error. There are different causes about this problem. We can troubleshot this problem several ways.
Misspelling is number one problem especially novice users or beginners. Here is an example
In this example we try to run nmap but misspelled it. Ubuntu provides some help by listing suggestion about the correct command.
Path Is Not Correct
Path is used to specify commands locations. If command location is not specified in PATH environment variable we can get an error like “The command could not be located”
We can solve this by adding /usr/bin to the PATH environment variable and export it like below.
$ export PATH=$PATH:"/usr/bin"
We generally assume that application is all ready installed. But default installed applications and commands changes from distribution to distribution or release from release
Hopefully Ubuntu provides information about the command and how to install it.