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Top Forums Shell Programming and Scripting for loop iteration and shell programming startup Post 302589982 by methyl on Friday 13th of January 2012 09:33:04 AM
Old 01-13-2012
Java

Quote:
question :how can i iterate to next item in for loop with the loop
e.g

for i in `cat abc.txt`
do
echo $i // this will display first line
i=$i+1; // this doesnt work for me.
echo $i; //this will display secound line
done
If we are working with lines, we do not want to expand the entire file "abc.txt" on the "for" line and then read it word by word.
We need to read each line one-by one with a method which preserves the record construct.
Code:
cat abc.txt | while read line
do
          echo "${line}"          # Display line
done

To make the extra read in the while loop:
Code:
cat abc.txt | while read line
do
          echo "${line}"          # Display first line and every odd-numbered line
          read line                  # Read even numbered lines
          echo "${line}"           # Display 2nd line and every even-numbered line
done


Don't understand your second question. Not clear which file is which or what the process is.
This User Gave Thanks to methyl For This Post:
 

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Archive::Zip::MemberRead(3)				User Contributed Perl Documentation			       Archive::Zip::MemberRead(3)

NAME
Archive::Zip::MemberRead - A wrapper that lets you read Zip archive members as if they were files. SYNOPSIS
use Archive::Zip; use Archive::Zip::MemberRead; $zip = Archive::Zip->new("file.zip"); $fh = Archive::Zip::MemberRead->new($zip, "subdir/abc.txt"); while (defined($line = $fh->getline())) { print $fh->input_line_number . "#: $line "; } $read = $fh->read($buffer, 32*1024); print "Read $read bytes as :$buffer: "; DESCRIPTION
The Archive::Zip::MemberRead module lets you read Zip archive member data just like you read data from files. METHODS
Archive::Zip::Member::readFileHandle() You can get a "Archive::Zip::MemberRead" from an archive member by calling "readFileHandle()": my $member = $zip->memberNamed('abc/def.c'); my $fh = $member->readFileHandle(); while (defined($line = $fh->getline())) { # ... } $fh->close(); Archive::Zip::MemberRead->new($zip, $fileName) Archive::Zip::MemberRead->new($zip, $member) Archive::Zip::MemberRead->new($member) Construct a new Archive::Zip::MemberRead on the specified member. my $fh = Archive::Zip::MemberRead->new($zip, 'fred.c') setLineEnd(expr) Set the line end character to use. This is set to by default except on Windows systems where it is set to . You will only need to set this on systems which are not Windows or Unix based and require a line end different from . This is a class method so call as "Archive::Zip::MemberRead"->"setLineEnd($nl)" rewind() Rewinds an "Archive::Zip::MemberRead" so that you can read from it again starting at the beginning. input_record_separator(expr) If the argument is given, input_record_separator for this instance is set to it. The current setting (which may be the global $/) is always returned. input_line_number() Returns the current line number, but only if you're using "getline()". Using "read()" will not update the line number. close() Closes the given file handle. buffer_size([ $size ]) Gets or sets the buffer size used for reads. Default is the chunk size used by Archive::Zip. getline() Returns the next line from the currently open member. Makes sense only for text files. A read error is considered fatal enough to die. Returns undef on eof. All subsequent calls would return undef, unless a rewind() is called. Note: The line returned has the input_record_separator (default: newline) removed. getline( { preserve_line_ending => 1 } ) Returns the next line including the line ending. read($buffer, $num_bytes_to_read) Simulates a normal "read()" system call. Returns the no. of bytes read. "undef" on error, 0 on eof, e.g.: $fh = Archive::Zip::MemberRead->new($zip, "sreeji/secrets.bin"); while (1) { $read = $fh->read($buffer, 1024); die "FATAL ERROR reading my secrets ! " if (!defined($read)); last if (!$read); # Do processing. .... } AUTHOR
Sreeji K. Das <sreeji_k@yahoo.com> See Archive::Zip by Ned Konz without which this module does not make any sense! Minor mods by Ned Konz. COPYRIGHT
Copyright 2002 Sreeji K. Das. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.18.2 2014-01-08 Archive::Zip::MemberRead(3)
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