Home / ubuntu / Questions / 1183849
Accepted
NerdOfLinux
Asked: 2019-10-26 12:09:12 +0800 CST

Why do empty quotes result in different output that nothing?

  • 772

When I run either of the following in the terminal:

''

""

I get the following output:

Command '' not found, but can be installed with:

sudo apt install libpam-mount      
sudo apt install openssh-server    
sudo apt install openvswitch-common
sudo apt install openvswitch-switch
sudo apt install php-common        
sudo apt install bpfcc-tools       
sudo apt install mailutils-mh      
sudo apt install mmh               
sudo apt install nmh

But, when I just press enter, nothing happens. Shouldn't these two cases have the same output of nothing?

server command-line bash apt

1 Answers

  1. Best Answer

    When you press enter it's just an empty line (zero tokens). When you enter '' there is a'' token (even if it is an empty string) so something tries to execute it(*). On my 16.04:

    >>>''
: command not found

    You can also try to execute space:

    >>>' '
 : command not found

    So the package suggestion mechanism is a bit buggy on your distro.

    (*) Also, compare plain ls vs ls ''

    • 3