Shell Programming and Scripting

Yes and no: programming is first and foremost about planning and you first need to define (in a painstakingly precise way) what exactly you do want: do you want to enter the user file names? Or filename-masks (like i.e. "enter abc and the script should process all files named abc[something].txt"). Or every file in a certain path when a directory is entered. (Maybe only files with a certain ending in said directory.) .....

You see, the possibilities are endless and as long as you do not explain exactly here (instead of only in general terms) what it is you want to achieve i can only help you in a general way.

First off: good attitude! Thecode is meant to play around with it. Taking it apart and trying to understand how it works is how you learn the trade.

Second: no, that is not a typo! To help me keep track of my variables i acquired the habit of using "Hungarian Style Notation": a system where a set of prefixes to the variable name explains what the content is (or should be). In this case "a" stands for "array" and "f" stands for a path name (from "file"), so "afFile" is an array of path names named "File".

You do not need to keep this convention and there are a lot of very good programmers who do not use this or use it differently. For me it is helpful, so i use it. As you go along you will acquire your own style at some point, but the one thing you should always try to achieve is: be consistent, at least with yourself. If you do something in a certain way, do it always this way. If you use Hungarian Style Notation then use it always - or not at all! This is what will your ode make easy to grasp and that will make it easier to maintain it.

I hope this helps.

bakunin

Apologies for how I went about this, I thought I could get away with just getting help with a part of it because I really do want to do this myself. I did not come asking for help lightly, but I was so far in the weeds on this one that I figured it would be best.

The entirety of the script's job is:

1: Prompt user from which machine on the network they would like to pull files

2: ssh to that machine and ls -lthr directory a and b

3: copy files chosen by the user from directories a and or b on the remote host to a given directory (/tmp) on the localhost

I've been attempting to modify the script as needed to do the ssh'ing and making the commands work on the remote machine. Like I said, I was trying to do as much as possible myself so that I would learn. That being said, I think this was harder than I anticipated it would be.

---------- Post updated at 09:44 PM ---------- Previous update was at 09:40 PM ----------

As for code, I have:

Code:

 echo "From which machine would you like to pull files?"
  
 read machine
  
 ssh -q $machine ls -lthr /directorya /directoryb
  
 echo "Which files would you like to copy?"
  
 read -a files

and then I've entered the code you wrote earlier in the thread but edited to ssh :

Code:

pWorkFile ()
{
typeset fFile="$1"                       # $1 holds the parameter with which it was called
typeset fPathA="/some/where"
typeset fPathB="/else/where"

if   ssh $machine [ -e "${fPathA}/$fFile" ] ; then
     ssh $machine scp "${fPathA}/$fFile" "($hostname|cut -d. -f1):/$fFile"
elif ssh $machine [ -e "${fPathB}/$fFile" ] ; then
     ssh $machine scp "${fPathB}/$fFile" "($hostname|cut -d. -f1):/$fFile"
else
     print - "Neither ${fPathA}/$fFile nor ${fPathB}/$fFile exists."
fi

return 0
}


# -------------------------------------- start of main program
typeset afFile[1]="file.foo"            # my list of fixed files
typeset afFile[2]="file.bla"
typeset afFile[3]="file.other"

typeset -i iCnt=0                        # a counter to process the array

(( iCnt = 1 ))
while [ $iCnt -le ${#afFile[@]} ] ; do
     pWorkFile "${afFile[$iCnt]}"
     (( iCnt += 1 ))
done

exit 0

---------- Post updated at 09:45 PM ---------- Previous update was at 09:44 PM ----------

I have tried to get them to work together playing around with it, but I haven't been able to get it to work.

If you call your variable afFile, why should it be a typo to refer it in this way?

However, your typeset statements are odd, and I don't quite get, what exactly you want to achieve.

Since the filenames are varying, you first decide, how the user should pass the names to your script. In your script, you did it with a

read -a files

which is technically possible, but interactively asking the user for a list of filenames is maybe not very convenient.

But, if you want to do it, go ahead; you will then have the names of the files stored in an array called 'files', and you could access the individual elements by ${files[0]}, ${files[1]} etc. However, accessing the files by index won't be necessary in your case, because you want to loop over these files and process each file separately, and the best way to process this array would be like this

Code:

for file in ${files[@]}
do
        ... code to process file $file
done

BTW, if you really want to request the files using the read -a command, you should add in your prompt some instruction to the user, how the files need to be input; for example: "Please enter the filenames to be processed, separated by spaces".

One disadvantage of this solution is, that it doesn't work, if the file path entered by the user contains spaces.

Because didn't we say it was called fFile when we said:

Code:

 typeset fFile="$1"

?

In this case, all the user must do is double click and then middle click because the ls -lthr from earlier in the code makes it quick and easy to pick and choose the files you want and there's not really a good way to pick them script wise, until we have AI, a human will have to do this part.

Noted, but I'm still not sure how to make it so that it checks if the file exists, ssh's to the machine, copies the files back to local host if it exists or simply tries the same stuff in the second directory, elsewise, it reports that the file doesn't exist.

Didn't know this, thank you. The array will still work, though. No spaces in the file names.

Yes, but in the last posting, there was a variable named afFile, so I though the name is OK. Of course you can name a variable as you like.

In any case, I wonder why you use typeset here. You are allowed to do it, but you can equally well write tFile="$1" .

---------- Post updated at 10:21 AM ---------- Previous update was at 10:18 AM ----------

Well, this is an unrelated issue, and I think you should make several discussion threads out of this, lest the conversation will be confusing.

So, for now, you have broken down the problem to the point where you have a single file name, which you need to process somehow. Now you have new problems: Checking the existence of a file. Copying the file. And what else more. Each of these problems is independent, so make a new posting out of each.

This piece was the entire reason for this post in the first place.

This was not clear to me, because you initially asked about a specific error message you got, and then the thread focused on this problem.

Still now, it is not clear to me what exactly you would like to now. In any case, all the other points you mention - copying, checking and so on - should better go to different threads, because each of them can be discussed separately (and, depending on your environment, might have non-trivial aspects to discuss).

I suggest to start separate threads for each item, and also indicate what exactly is your problem in each case.