writting progress to cl on one line

[sde]

I use php4-cgi to write scripts on my linux box. The scripts are going through lots of data and I want to print output to the screen as it runs.

Printing output to the screen is no problem, but it prints out line for line, and soon enough your screen is full of lines.

I've seen a perl program that keeps all the output on 1 line. it updates the same line till it is complete.

so, even though it prints a new value for each % it is complete, here is how a program calld "someprogram.pl" would look after running it:

$ ./someprogram.pl
[ 50%] Complete

does that make sense? normally it would read

$ ./someprogram.pl
[  1%] Complete
[  2%] Complete
[  3%] Complete
.. and so on

Any ideas how to keep output to 1 line?

[ender]

This might be a little late, and you might have figured it out already. What you are looking for is the Carriage Return character. This can be accomplished by printing the "\r" special character. This resets the cursor to the beginning of the same line you are currently on. I recently wrote a colored progress bar for the terminal in perl this way.

This makes windows version of newlines a lot easier to understand. Windows requires the full \n\r to get to the next line. I assume it is because they don't automatically reset the cursor to the beginning of the line when the cursor moves down. Therefore, you need the \r in there. Linux does this automatically, and so we get fun battles where lines don't look right in windows when they looked fine in linux.

Although you probably knew that already, so I'm gonna stop now. However, before I sign off, I will mention that if you are looking for cool stuff to do to a 'standard' vt200 terminal (which most linux terminals emulate anyway) the following link will help: Terminal Escape Sequences

Hope this helps. Good luck!

- Ted

[sde]

Thanks Ted .. nice to see you here again. I did not know that, I actually gave up and just settled with the multi-line output. This gives me something to play with. I appreciate it!

[sde]

well to bring this up again, is there anyway to do it with bash scripting? i can get it to work if i use php or perl, .. but not if i write a simple bash script.

[ender]

You should be able to do it in bash. Although determining the percentage to fill might be a little trickier than I would like it to be. The overall concept is the same though. I'm sure you knew this, but be sure to do 'echo -e' to enable interpretation of escape sequences. I think this may be dependent upon which shell you use. However I do know that /bin/echo is pretty much a constant.

The way you can do your percentages if you want to is to is pipe any calculation you want into bc and read the answer. For example, finding 2+2 : 'echo "2+2" | bc" will result in 4 on stdout.

The following should work for just a percentage though:

#!/bin/bash

echo "Start"

for i in 1 2 3 4
do
  percentage=`echo "scale=2; $i/4 * 100" | bc -l`
  echo -en "\r$percentage %"
  sleep 1
done

echo -e "\nDone!"

This should get you started. Oh, the -n option for echo suppresses the newline from being printed after the echo 'echos' something. Good Luck!

-Ted