topic Re: Command qns again... in Operating System - Linux

Command qns again...

Avery_1 — Fri, 25 Apr 2003 03:15:09 GMT

1.What is the scope of a local variable?

2.Does the Bourne shell support job suspension and resumption?

3.What other command/commands can one use to list the process running on a machine?

4.What does the echo here outputs?

name="Mike"

export name

echo $name

sh

echo $name

name="Ben"

export name

echo $name

exit

echo $name

:Thanks...

Re: Command qns again...

Balaji N — Fri, 25 Apr 2003 03:33:01 GMT

hi,

first, i would recommend you to pick up a good book on shell programming and read it. solves most of your queries and gives a good insight.

1. it is available in that shell. when the shell is terminated, the local variable does not exist. all local variables set in this shell are also avaiable by any shells spawned by this shell. (will help u understand q.4)

2. yes. ctrl+z top stop and then fg to start executing it again. actually this ctl+z can be modified. do an stty -a and see the value for susp.

3. ps, top, pstree etc. and if you can manipulate the psuedo file system /proc for information as well.

4. first and second echo will be mike. since you are changing the value after that, the third will be ben and after that the shell exits. so the changed value of name is not available. and name echoes the value of mike again.

hth
-balaji

Re: Command qns again...

Avery_1 — Fri, 25 Apr 2003 03:43:50 GMT

thanks 4 replying but i am comparing with my answers...that's all...that is y i need u guy's help...i am a newbie in linux...

Re: Command qns again...

Balaji N — Fri, 25 Apr 2003 03:53:15 GMT

ph yes. you are welcome.
-balaji

Re: Command qns again...

Ramkumar Devanathan — Fri, 25 Apr 2003 04:24:04 GMT

Sophia,

1. local variables declared with the local builtin (bash), are local to the function within which they are defined. They can be declared only within a function. Apart from this, what balaji says holds good for variables defined in the scripts.
function abc()
{
local temp=0 # temp will be local variable in function abc() with local scoping
...
}

2. To add to what Balaji mentions, bg will resume a suspended process in the background.

$ bg

will resume the first of the suspended processes and run it in the background.

3. ps x, ps eaf - man ps generally... also looking at /proc/ is a cool idea, balaji.

4. Nothing to add over what Balaji has added.

HTH.

- ramd.