Need some help with a bash script Post: 302990950

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Homework and Emergencies Homework & Coursework Questions Need some help with a bash script Post 302990950 by RudiC on Friday 3rd of February 2017 09:22:36 AM

02-03-2017

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Quote:

Originally Posted by Eggsy

Thanks for your answer. Would you mind helping me to understand how exactly those statements work then.

I'm glad to help, but: instead of delivering ready made answers, I prefer to make you cogitate and find the answers yourself.

Quote:

Is my assumption that "grep s>/dev/null" and "grep r>/dev/null" check whether or not a filename contains an S and an R correct?

Partly. Why should grep s try to match an S ? And, recheck your conclusions (what does and when applies the || ?).

Quote:

So looking over it again, for 2. would this mean it's invoked 15 times too, because it checks every single file.

Correct!

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And as for 3. could it be 7 times, since you only reach the "grep r>/dev/null" part when it found an S in the name (since there are only 7 files with an S)?

Count again...

---------- Post updated at 09:10 AM ---------- Previous update was at 09:02 AM ----------

Quote:

a) I believe the filenames were actually all lower case. (As a german, we capitalize names, so that was my mistake when I wrote this down)

So...?

Quote:

b) || means we only reach the right side, when the left side is true, iirc. So once it found a filename with an "s", it checks for an "r"?

Please double check the || operator in shell scripts.

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1. We have 15 items. So it goes through the list of files until every single one was checked?

And how is end-of-file detected?

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2. Also 15 times, since it checks every single item for an "s"?

Drop the "also"; then, yes.

Quote:

3. 7 times, since we only reach the second part, when we found an item with an "s"

see answer to b)

Quote:

4. 3 times, since we only have reach that part, when we found an item with an "s" and an "r"

see answer to b)

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