/dev/chat

9:10 AM

Hi, Is anyone here?

(no?)

;-)

@alamin Yes, I'm most definitely here. The only problem is that my cup of coffee isn't.

can i ask a simple question

(coffee cup found, all is well)

@alamin Do it

what is the function of set?

set command

set arg1 arg2 arg3

why we need to use this command for?

@alamin That will set the positional parameters $1, $2 and $3 to the specified values.

Then you could do for thing; do ... done to iterate over them.

9:18 AM

when we run a script don't we give the args there and the positional parameters are made automatically from those args... so how this command can help me. is there any more usage?

It's not used that way often. I would have to dig out a real world example... hold on.

all right .... i will wait for the response

set foo bar dream sky blue

for var in $@

echo $var

done

OUTPUT:

foo
bar
dream
sky
blue

You don't even need the in $@.

why?

don't I need the collection?

Because for will use the positional parameters if not given anything else.

9:25 AM

so how do I write this?

for var
do

yep

well, let me try

yes it works...

another question came to my mind?

setting to a null string, isn't equivalent to unsetting it

what does that mean?

Not really the same thing. There was a question about this a while ago.

Another Thing Are you Indian? Cause Your Name Suggest it ...

A: Are the null string and "" the same string?

Yes, a null string in that context is a string of length 0 containing no byte at all. In bash: var= var='' var="" var=$'' var=$"" var=$(true) # or any command that outputs nothing or only newline # characters var=`true` var=${null_or_unset_var} var=''""$''$""$(true)"`true`" But als...

@alamin :-) No, not Indian. Long story...

Also: unix.stackexchange.com/a/121558/116858

9:30 AM

I would like to hear it some day :D

set is more often used for setting shell options, as with set -x.

all right... tell me more ... like setting environment variables or something?

@alamin No, in bash, type help set to get its documentation.

2 hours later…

11:36 AM

anyone?

Just me, sorry :-)

11:57 AM

@Kusalananda Apparently today is shell tutoring day.

1 hour later…

1:01 PM

@FaheemMitha Every day is shell tutoring day in one corner or the other :-)

1 hour later…

2:11 PM

Closing that wa a bit harsh... unix.stackexchange.com/questions/390091/…

Esp. since I just solved it ;-)

1 hour later…

3:22 PM

@Kusalananda Do you want me to cast a reopen vote? I see there is one - is that you?

@FaheemMitha Yes, that's me. I dunno. The question is clear to me...

@Kusalananda So that's a yes on casting a reopen vote?

You should know that one of my idiosyncrasies is that I like direct answers to questions.

If I lived in a romantic comedy it would probably be a charming foible.

3:50 PM

@FaheemMitha :-) It's a "Yes, if you think the question is worth reopening".

I hate telling people what to do.

@Kusalananda I'll take your word for it. It's not life or death.

@Kusalananda That's very noble of you.

I see it's got -3, so some people are not impressed.

Actually, it's indeed unclear what the question is asking. Did you figure it out?

Well, a good answer can still be written. Yes, he wants to get all lines between the first and lost occurance of a certain word.

This is actually non-trivial and quite an interesting problem.

Oh, I see. He wants section bookended by the End delimiter to be preserved.

You see my solution in comments, but I could write more about it.

Is that correct?

3:53 PM

Yes, I believe so.

Though if so, he's expressing it very poorly.

I'd suggest rewording it. I'll vote to reopen, but it would encourage more people to do so.

The naive solution with sed doesn't work: /End/,/End/p

@Kusalananda Does your comment not work, then?

My comment works

@Kusalananda Ok.

3:54 PM

... by working on the beginning of the file, reversing it and doing the same thing again before reversing it a second time.

I'd improve the question's wording.

Do so. I need to feed my girl.

BTW, am I correct here?: stackoverflow.com/a/46025153/4941495

Regarding let and expr