difference

nagavinodh · 04-06-2010, 01:47 AM

Hi,

What is the difference between #./a.shand #sh a.sh in linux?
And also su - oracle and su oracle?

EricTRA · 04-06-2010, 01:58 AM

Hello,

These questions sound very much like homework and the answers can very easily be found using Google. If you just ask exactly what you posted in Google, you'll get complete answers within the first 5 links. Please put in some time and work instead of relying on LQ to answer the simplest questions.

Kind regards,

Eric

affinity · 04-06-2010, 02:00 AM

'su -' mimics the act of logging in, so the user's environment variables and profile are sourced. sh invokes the shell, whereas the . means 'source' so it doesn't matter what type of executable is being called.

linuxlover.chaitanya · 04-06-2010, 02:00 AM

Have you tried yourself. Its not that hard.
For the first issue, sh a.sh will run the script as sh shell script. If you run it as bash a.sh it will run as bash script. While ./a.sh will do the same but if it is written using different shell than what you are running then you might get issues.

For second, su - oracle will take you to home directory for oracle user but su oracle will keep you in the current and not change to oracle home directory.

nagavinodh · 04-06-2010, 08:06 AM

Quote:

Originally Posted by linuxlover.chaitanya

Have you tried yourself. Its not that hard.
For the first issue, sh a.sh will run the script as sh shell script. If you run it as bash a.sh it will run as bash script. While ./a.sh will do the same but if it is written using different shell than what you are running then you might get issues.

For second, su - oracle will take you to home directory for oracle user but su oracle will keep you in the current and not change to oracle home directory.

Hi,

Thanks for reply.

I tried it.but confusing.
when execute the cd then enter and pwd which shows the home directory?

su oracle also returns same thing as su - oracle except 2 line

1,[root@per1 ~]# su oracle
2[oracle@per1 root]$ pwd
3,/root
4,[oracle@per1 root]$ cd
5,[oracle@per1 ~]$ pwd
6,/home/oracle
7,[oracle@per1 ~]$

And please tell about ./a.sh ?

pixellany · 04-06-2010, 08:10 AM

Quote:

Originally Posted by affinity

.......the . means 'source' so it doesn't matter what type of executable is being called.

Not in this context........

"./file" means "run file in the current directory"----the "." means current directory.

linuxlover.chaitanya · 04-06-2010, 08:13 AM

Code:

1,[root@per1 ~]# su oracle
2[oracle@per1 root]$ pwd
3,/root

You can see here you are in root's home directory.

While if you do su - oracle and then give pwd command you will notice /home/oracle as the output of pwd.

linuxlover.chaitanya · 04-06-2010, 08:15 AM

And about your second issue, you have already received replies. ./a.sh will try to run the script which is in current directory as already said by pixellany. And it will try to run using the shell user is logged in into.

affinity · 04-06-2010, 10:07 PM

Quote:

Originally Posted by pixellany

Not in this context........

"./file" means "run file in the current directory"----the "." means current directory.

Ah, thank you for the correction, this whole time I thought it meant something different when used to execute a program.