Modify the value of $PATH on linux platform

With the purpose of adding '/usr/sbin' to $PATH.
1.Modify the value of $PATH for user account.

Firstly, check the value of $PATH as below, '/usr/sbin' is excluded.

[sandy@localhost ~]$ echo $PATH
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/sandy/bin

Secondly, add the needed path in .bash_profile, the blue line is addition.
Before:

[sandy@localhost ~]$ cat .bash_profile
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:$HOME/bin

export PATH
[sandy@localhost ~]$

After:

[sandy@localhost ~]$ cat .bash_profile
# .bash_profile

# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi

# User specific environment and startup programs

PATH=$PATH:$HOME/bin:/usr/sbin

export PATH
[sandy@localhost ~]$

And thirdly, re-import the file .bash_profile or relogin the session, the last step is confirming the value of $PATH.

[sandy@localhost ~]$ source .bash_profile
[sandy@localhost ~]$ echo $PATH
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/sandy/bin:/home/sandy/bin:/usr/sbin
[sandy@localhost ~]$

As above, $PATH is reset only for account 'sandy', let's take a look at the value of $PATH for account 'rock' as follow '/usr/sbin' is excluded.
 ex

[rock@localhost ~]$ echo $PATH
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/rock/bin
[rock@localhost ~]$

2.Modify the value of $PATH for all accounts.

Login your session as root, then modify /etc/profile as we just have been done for .bash_profile.
Then you can find the '/usr/sbin' is added into $PATH for all accounts on this server. Also take 'rock' as an example to confirm.

[rock@localhost ~]$ echo $PATH
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/sbin:/home/rock/bin
[rock@localhost ~]$