Impossibilitus Interruptus ...

[Langstracht]

I am trying to write a script which will successively show the last, second last and last, third last second last and last ... and so on ,,, lines of a file, pausing after each increment and waiting for an "Enter" (or whatever) before continuing.

The displaying of the file content is covered by:

count=10

i=1

while [ $i -le $count ]

do

tail -$i filename.txt

i=`expr $i + 1`

done

Which seems to work just fine.

BUT I have been unable to accomplish the pause.

It seems that "read -p" and "pause ()" are both supposed to work. But I have been unable to get them to do so.

Anyone have any ideas?

Help muchly appreciated ...

[QIII]

Moved to Programming Talk.

[steeldriver]

how about

i=1; while true; do read x; tail -n $((i++)) file; done

[Langstracht]

Thanks for the lightning response.

Alas it snagged me an error message - arithmetic expression: expecting primary: "i++"

I could pretend I knew what that meant ...

[Crusty Old Fart]

In keeping with your coding style, which is much different than mine, your script worked for me when I added the blue line shown in the code box below:

#!/bin/bash
set -e

count=10
i=1
while [ $i -le $count ]
do
tail -$i filename.txt
i=`expr $i + 1`
read -p "Hit [Enter] to continue or [Ctrl+C] to abort."
done

I'd have done it like this:

#!/bin/bash
set -e

for i in {1..10}; do
  tail -$i filename.txt
  read -p "Hit [Enter] to continue or [Ctrl+C] to abort."
done

exit 0

As you can see, steeldriver would have made it even shorter.

[steeldriver]

Thanks for the lightning response.

Alas it snagged me an error message - arithmetic expression: expecting primary: "i++"

I could pretend I knew what that meant ...

It probably means you're running it in sh (i.e. dash) rather than bash

[Langstracht]

In response to steeldriver - if you could tell me how to change that it would be most appreciated.

In response to Crusty Old Fart - alas it does not work for me. The "Hit [Enter] to continue or [Ctrl+C] to abort." message shows up as displayed lines (albeit with the addition of ":read: 17: arg count") in between the various sections. Not a pause to be seen ,,,

[steeldriver]

Well the default shell is usually bash - so you must be doing something to change it to dash - either

• you changed your default shell to /bin/sh
• you are running this inside a shell script with a #!/bin/sh shebang at the top
• you are explicitly invoking it via sh on the command line i.e. sh ./myscript

If you don't do any of those things, you should get a bash shell

[Crusty Old Fart]

It would be nice to see the entire content of your script in a code box. Otherwise, we're just guessing as to why what works for us isn't working for you.

[Langstracht]

In response to steeldriver - if I did any of those things it was inadvertently. Info as to how "normal service might be resumed" would be very helpful.

In response to Crusty Old Fart - the sum total of the script was on the page. Sorry I don't see a "code box option".