A console output question

[arunhorne]

Monks

I have written a perl script that reads a very large file line by line and processes it. I want to give the user some feedback, i.e. the current line. So I want to write to the console something like:

Current line is: 31721 

I could do it with a print statement, but this produces a new line for each update. Is it possible to overwrite the previous line, i.e. 31721 becomes 31722 and gives the illusion of a counter and looks much neater?

Thanks,

____________
Arun

[Chmrr]

Use print "Current line is: $line\r" or some varient thereof. \r moves the 'cursor' to the start of the line, without moving down a line. You will need to turn buffering off ($|++) for this to work.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'

[greenFox]

See this How to UPDATE rather than append to STDOUT? node.

--
my $chainsaw = 'Perl';

[demerphq]

I like to use the following:

use Tie::Cycle;

tie my $spinner, 'Tie::Cycle', ["\r-","\r\\","\r|","\r//"];
my $spin_every=10;
while (<>) {
  print $spinner unless $. % $spin_every;
  # yada-yada-yada
}

The result is a spinning line. Excellent for indicating the program is still alive. The use of mod prevents the output fom happening so often that printing slows the script down noticibly.

Yves / DeMerphq
---
Writing a good benchmark isnt as easy as it might look.

[strat]

Btw: with a while(<...>) - loop, you can find out about the current line by reading the content of the special Variable $. as long as the Filehandle is still opened. But if you change the variable $/ , $. will give you the number of read blocks (what a block is, is said in $/ ).

Best regards,
perl -e "s>>*F>e=>y)\*martinF)stronat)=>print,print v8.8.8.32.11.32"