[Bio-Linux] BioLinux 8 question - Adding and removing Paths - Velvet - correction

[Tony Travis]

On 12/04/15 21:49, Zain A Alvi wrote:
> [...]
> On a side note.  I had to sudo cp -ai velvetg velveth /usr/local/bin
> as I was receiving Permission Errors.  Is this normal even when I am
> admin and not root in Bio-Linux/Ubunut?  I know to access root you
> have to go through sudo su and it should be rarely used.

Hi, Zain.

Yes, it's normal: Ubuntu discourages use of the "root" account for
external logins because this is a serious security hole. The
'Administrator' accounts are accounts with permission to use "sudo".
Ordinary user accounts are not permitted to use the "sudo" command.

BTW, it is redundant to use:

  sudo su

It's better to use;

  sudo -i

This gives you a "root" shell with the same environment as if you had
logged in as "root", but without exposing your computer to e.g.
'brute-force' attacks, which target external SSH logins on the "root"
account.

> If I ever want to add other applications, I would then continue
> adding/copying them into /usr/local/bin and adding the paths to
> ~/.zshrc
> 
> Is there any way to change the order for $PATH?

You can edit the PATH variable and export it, but it is best to keep
your changes to a mimimum: Either by adding another directory before the
current PATH e.g.:

  export PATH=/before_path:$PATH

Or, after the current PATH e.g.:

  export PATH=$PATH:/after_path

You have to 'rehash' the PATH unless you start a new shell:

  hash -r

HTH,

  Tony.

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