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Full Discussion: Perl how to move pointer to previous line in a txt file?
Top Forums Shell Programming and Scripting Perl how to move pointer to previous line in a txt file? Post 302161414 by tqlam on Thursday 24th of January 2008 12:24:25 PM
Old 01-24-2008
Perl how to move pointer to previous line in a txt file?
I have a text file that has blocks of text. Each block starts with ### and ends with End_###.
I wrote a perl script to search a string from line 2 (ignore any line starts with ###) of each block
if matched, need to print that whole block. According to the input file in below, it will print blocks #02, #04, #05.
Here is my question, I have no problems matching the SEARCH_STR, but once matched, how do I move back previous lines?
e.g. in block #02, matched in line 3, but I need to print lines 1 & 2.

Thanks in advance for any help!

MY SCRIPT:
=========
#!/46020/local/bin/perl -w
#
if ($#ARGV != 0) {
print "You must provide a search criteria.\n";
exit;
}
my $query = $ARGV[0];
my $INPUT = "/mypath/inputFILE.txt";
my $line;
my $tag = 0;
my @results = ();

open (FILE, "<$INPUT") or die "Cannot open '$INPUT' file: $!";
while ($line = <FILE>) {
next if ($line =~ /^#[0-9][0-9].* - / || $line =~ /^\s*$/);
if ($line =~ /$query/i) {
$tag = 1;
}
if ($line =~ /^End_#/ && $tag == 1) {
push (@results,$line) if ($tag == 1);
$tag = 0;
}
push (@results,$line) if ($tag == 1);
}
close (FILE);
print "@results\n";
exit;


INPUTFILE:
========
#01 - block start line here
some text here
more text here
more lines
more lines
more lines
End_#01

#02 - block start line here
some text here
this line contains the SEARCH_STR and something
more lines
more lines
End_#02

#03 - block start line here
some text here
more text here
more lines
more lines
more lines
End_#03

#04 - block start line here
some text here
more lines
more lines
the SEARCH_STR is here and something
some text here
more lines
more lines
more lines
End_#04

#05 - block start line here
some text here
more lines
the SEARCH_STR is here and something
more lines
End_#05


#06 - block start line here
some text here
more text here
more lines
more lines
more lines
End_#06
 

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LEARN ABOUT OPENSOLARIS

wrjpgcom

wrjpgcom(1)							   User Commands						       wrjpgcom(1)

NAME

       wrjpgcom - insert text comments into a JPEG file

SYNOPSIS

       wrjpgcom [-replace] [-comment text] [-cfile name] [filename]

DESCRIPTION

       wrjpgcom  reads	the named JPEG or JFIF file, or the standard input if no file is named, and generates a new JPEG or JFIF file on the stan-
       dard output. A comment block is added to the file.

       The JPEG standard allows "comment" (COM) blocks to occur within a JPEG file. Although the standard does not actually  define  the  intended
       function  of COM blocks, they are widely used to hold user-supplied text strings. This enables you to add annotations, titles, index terms,
       and so on to your JPEG files, and later retrieve the COM blocks as text. COM blocks do not interfere with the  image  stored  in  the  JPEG
       file. The maximum size of a COM block is 64K, but you can have many COM blocks in one JPEG file.

       wrjpgcom  adds  a  COM  block,  containing text that you provide, to a JPEG file. Ordinarily, the COM block is added after any existing COM
       blocks, but you can delete the old COM blocks if you wish.

OPTIONS

       The following options are supported:

       -cfile name     Read the text for a new COM block from the named file.

       -comment text   Supply the text for a new COM block on the command line.

       -replace        Delete any existing COM blocks from the file.

OPERANDS

       The following operands are supported:

       filename        The name of the JPEG file to which you want to add text comments.

EXTENDED DESCRIPTION

       To add only one line of comment text, use the -comment option to provide the text on the command line.  Specify	the  comment  text  within
       quotes, so that the text is treated as a single argument. Longer comments can be read from a text file.

       If  you	specify  neither  the -comment nor the -cfile option, wrjpgcom reads the comment text from standard input. In such cases, you must
       supply an input image filename. You can enter multiple lines, up to 64KB. Type an end-of-file indicator, usually Ctrl-D, to  terminate  the
       comment text entry.

       wrjpgcom  does  not  add a COM block if the provided comment string is empty. Therefore, you can use -replace -comment "" to delete all COM
       blocks from a file.

EXAMPLES

       Example 1: Adding a Short Comment to in.jpg to Produce out.jpg

       example% wrjpgcom -c "View of my back yard" in.jpg > out.jpg

       Example 2: Attaching a Long Comment Previously Stored in comment.txt

       example% wrjpgcom in.jpg < comment.txt > out.jpg

       or

       example% wrjpgcom -cfile comment.txt < in.jpg > out.jpg

       In this example, 1000 is a number that is larger than the number of rows in the source file.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWjpg			   |
       +-----------------------------+-----------------------------+
       |Interface stability	     |Volatile			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       cjpeg(1), djpeg(1), jpegtran(1), rdjpgcom(1)

NOTES

       This man page was originally written by the Independent JPEG Group.  Updated by Breda McColgan, Sun Microsystems Inc., 2004.

SunOS 5.11							    26 Mar 2004 						       wrjpgcom(1)
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