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Come Join Us!Are you aComputer / IT professional?Join Tek-Tips Forums!Talk With Other MembersBe Notified Of ResponsesTo Your PostsKeyword SearchOne-Click Access To YourFavorite ForumsAutomated SignaturesOn Your PostsBest Of All, It's Free!Join Us!*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.Posting GuidelinesPromoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click HereTek-Tips Posting PoliciesContact US read a line from a file and writing to the same line in the filethread219-1428684 ForumSearchFAQsLinksMVPsForumSearchFAQsLinksMVPs read a line from a file and writing to the same line in the file read a line from a file and writing to the same line in the file bcdixit (TechnicalUser)(OP)20 Nov 07 14:25How do I write to the same line in a file after reading from the that line.#!/usr/contrib/bin/perl$i = "c.txt";$flag = 0;if (-e $i ){ open(RW,"+", $i); print RW "0"; $flag = 1; }if($flag == 0){ while() { $tmp = $_; } $tmp=$tmp+1; print RW $tmp;} close RW;I want this program to create a file called c.txt if it doesnot exist and on the first run of the perl script it should write a '0' to first line in the file. the next time I run the script, it should read the first line(i.e. a 0), increment it by 1 and then re-write to the same line. i.e. the first line on the file should be written with '1'. Currently when i run the script for the first time, it correctly write a '0' on the first line but when I rerun the script it appends the incremented value i.e. a '1' (writes a '01') on the first line. I expect it to write a '1' on first line. Any help is appreciated. Thanks RE: read a line from a file and writing to the same line in the file travs69 (MIS)20 Nov 07 14:40use Tie::File ??
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Travis - Those who say it cannot be done are usually interrupted by someone else doing it; Give the wrong symptoms, get the wrong solutions;
RE: read a line from a file and writing to the same line in the file ishnid (Programmer)20 Nov 07 14:52Absolutely. Tie::File would be the way to go. RE: read a line from a file and writing to the same line in the file MillerH (Programmer)20 Nov 07 15:44perlfaq5 - How do I change one line in a file/delete a line in a file/insert a line in the middle of a file/append to the beginning of a file?- Miller RE: read a line from a file and writing to the same line in the file bcdixit (TechnicalUser)(OP)20 Nov 07 16:48is there another way of doing this...I am getting this ...Can't locate TIE/File.pm in @INC (@INC contains: /opt/perl5/lib/5.6.1/PA-RISC2.0 /opt/perl5/lib/5.6.1 /opt/perl5/lib/site_perl/5.6.1/PA-RISC2.0 /opt/perl5/lib/site_perl/5.6.1 /opt/perl5/lib/site_perl .) RE: read a line from a file and writing to the same line in the file ishnid (Programmer)20 Nov 07 16:50It's case-sensitive. Tie::File, not TIE::File RE: read a line from a file and writing to the same line in the file bcdixit (TechnicalUser)(OP)20 Nov 07 17:02still the same error after ishnids comments. I don't think this module is availalle on the box....and its a pain in the axx to get the sysadmin to compile it. RE: read a line from a file and writing to the same line in the file ishnid (Programmer)20 Nov 07 18:03It's a pure Perl module so it doesn't need to be compiled. Have a look here for more on installing modules when you don't have root access. RE: read a line from a file and writing to the same line in the file KevinADC (TechnicalUser)20 Nov 07 19:17Very old version of perl, 5.6.1, might not have Tie::File. You can use perls inplace editor which is what Millers link will discuss. It's much more efficient than Tie::File anyway from what I have onserved.
------------------------------------------- Kevin, perl coder unexceptional! 
RE: read a line from a file and writing to the same line in the file KevinADC (TechnicalUser)20 Nov 07 19:18onserved = observed
------------------------------------------- Kevin, perl coder unexceptional!
RE: read a line from a file and writing to the same line in the file bcdixit (TechnicalUser)(OP)20 Nov 07 19:37I checked Millers Link.. sorry but can you help me understand what is the "inplace editor"? RE: read a line from a file and writing to the same line in the file ishnid (Programmer)20 Nov 07 21:28Miller's link actually recommends Tie::File, as it's standard from 5.8.0.Installing the Tie::File module only involves creating one directory, copying one file and adding one line to the top of your script.1) Create a directory called (for example) /home/username/modules/Tie2) Grab the source code from here and save it in a file called (following the example above) /home/username/modules/Tie/File.pm3) Then in your script, before you load the module with "use Tie::File;", add the following line:CODEuse lib '/home/username/modules'; RE: read a line from a file and writing to the same line in the file KevinADC (TechnicalUser)20 Nov 07 23:21using perl inplace editor:CODE#!/usr/contrib/bin/perluse strict;use warnings;my $i = "c:/perl_test/c.txt";if ( -e $i ){ local @ARGV = ($i); local $^I = '.bak'; while ( ) { print ++$_; }}else { open(RW, ">", $i) or die "$!"; print RW "0";}------------------------------------------------------------Pragmas (perl 5.8.8) used :strict - Perl pragma to restrict unsafe constructswarnings - Perl pragma to control optional warnings
------------------------------------------- Kevin, perl coder unexceptional!
RE: read a line from a file and writing to the same line in the file KevinADC (TechnicalUser)20 Nov 07 23:23this part:CODEelse { open(RW, ">", $i) or die "$!"; print RW "0";}better written as:CODEelse { open(RW, ">", $i) or die "$!"; print RW "0"; close RW; }
------------------------------------------- Kevin, perl coder unexceptional!
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