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Subject: File Contents
Date: Wed, 29 Apr 2009 09:26:38 +0800
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<DIV class=3DSECT1>
<H1 class=3DSECT1><A name=3DFILECONTENTS>8. File Contents</A></H1>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN430>Introduction</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ff7f50>defined</FONT> <FONT =
color=3D#00ffff>(</FONT>$line =3D &lt;DATAFILE&gt;<FONT =
color=3D#00ffff>))</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>chomp</FONT> $line<FONT =
color=3D#00ffff>;</FONT>
    $size =3D <FONT color=3D#98fb98>length</FONT> $line<FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT =
color=3D#00cd00>"$size\n"</FONT><FONT color=3D#00ffff>;</FONT>           =
     <FONT color=3D#bebebe># output size of line
</FONT><FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>&lt;DATAFILE&gt;<FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>chomp</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT =
color=3D#98fb98>length</FONT>, <FONT color=3D#00cd00>"\n"</FONT><FONT =
color=3D#00ffff>;</FONT>             <FONT color=3D#bebebe># output size =
of line
</FONT><FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#cdad00>@lines</FONT> =3D &lt;DATAFILE&gt;<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ff7f50>undef</FONT> $/<FONT =
color=3D#00ffff>;</FONT>
$whole_file =3D &lt;FILE&gt;<FONT color=3D#00ffff>;</FONT>               =
<FONT color=3D#bebebe># 'slurp' mode
#-----------------------------
#% perl -040 -e '$word =3D &lt;&gt;; print "First word is $word\n";'
#-----------------------------
#% perl -ne 'BEGIN { $/=3D"%%\n" } chomp; print if /Unix/i' fortune.dat
#-----------------------------
</FONT><FONT color=3D#ff7f50>print</FONT> HANDLE <FONT =
color=3D#00cd00>"One"</FONT>, <FONT color=3D#00cd00>"two"</FONT>, <FONT =
color=3D#00cd00>"three"</FONT><FONT color=3D#00ffff>;</FONT> <FONT =
color=3D#bebebe># "Onetwothree"
</FONT><FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"Baa baa =
black sheep.\n"</FONT><FONT color=3D#00ffff>;</FONT>     <FONT =
color=3D#bebebe># Sent to default output handle
#-----------------------------
</FONT>$rv =3D <FONT color=3D#98fb98>read</FONT><FONT =
color=3D#00ffff>(</FONT>HANDLE, $buffer, <FONT =
color=3D#cdcd00>4096</FONT><FONT color=3D#00ffff>)</FONT>
        <FONT color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> =
<FONT color=3D#00cd00>"Couldn't read from HANDLE : $!\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe># $rv is the number of bytes read,
# $buffer holds the data read
#-----------------------------
</FONT><FONT color=3D#98fb98>truncate</FONT><FONT =
color=3D#00ffff>(</FONT>HANDLE, $length<FONT color=3D#00ffff>)</FONT>
    <FONT color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> =
<FONT color=3D#00cd00>"Couldn't truncate: $!\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#98fb98>truncate</FONT><FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>"/tmp/$$.pid"</FONT>, $length<FONT =
color=3D#00ffff>)</FONT>
    <FONT color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> =
<FONT color=3D#00cd00>"Couldn't truncate: $!\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>$pos =3D <FONT color=3D#98fb98>tell</FONT><FONT =
color=3D#00ffff>(</FONT>DATAFILE<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"I'm $pos bytes =
from the start of DATAFILE.\n"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#98fb98>seek</FONT><FONT =
color=3D#00ffff>(</FONT>LOGFILE, <FONT color=3D#cdcd00>0</FONT>, <FONT =
color=3D#cdcd00>2</FONT><FONT color=3D#00ffff>)</FONT>         <FONT =
color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> <FONT =
color=3D#00cd00>"Couldn't seek to the end: $!\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#98fb98>seek</FONT><FONT color=3D#00ffff>(</FONT>DATAFILE, =
$pos, <FONT color=3D#cdcd00>0</FONT><FONT color=3D#00ffff>)</FONT>     =
<FONT color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> <FONT =
color=3D#00cd00>"Couldn't seek to $pos: $!\n"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#98fb98>seek</FONT><FONT color=3D#00ffff>(</FONT>OUT, =
<FONT color=3D#cdcd00>-20</FONT>, <FONT color=3D#cdcd00>1</FONT><FONT =
color=3D#00ffff>)</FONT>           <FONT color=3D#98fb98>or</FONT> <FONT =
color=3D#ffa500>die</FONT> <FONT color=3D#00cd00>"Couldn't seek back 20 =
bytes: $!\n"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>$written =3D <FONT color=3D#98fb98>syswrite</FONT><FONT =
color=3D#00ffff>(</FONT>DATAFILE, $mystring, <FONT =
color=3D#98fb98>length</FONT><FONT =
color=3D#00ffff>(</FONT>$mystring<FONT color=3D#00ffff>));</FONT>
<FONT color=3D#ffa500>die</FONT> <FONT color=3D#00cd00>"syswrite failed: =
$!\n"</FONT> <FONT color=3D#ffa500>unless</FONT> $written =3D=3D <FONT =
color=3D#98fb98>length</FONT><FONT =
color=3D#00ffff>(</FONT>$mystring<FONT color=3D#00ffff>);</FONT>
$read =3D <FONT color=3D#98fb98>sysread</FONT><FONT =
color=3D#00ffff>(</FONT>INFILE, $block, <FONT =
color=3D#cdcd00>256</FONT>, <FONT color=3D#cdcd00>5</FONT><FONT =
color=3D#00ffff>);</FONT>
<FONT color=3D#98fb98>warn</FONT> <FONT color=3D#00cd00>"only read $read =
bytes, not 256"</FONT> <FONT color=3D#ffa500>if</FONT> <FONT =
color=3D#cdcd00>256</FONT> !=3D $read<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT>$pos =3D sysseek<FONT color=3D#00ffff>(</FONT>HANDLE, <FONT =
color=3D#cdcd00>0</FONT>, <FONT color=3D#cdcd00>1</FONT><FONT =
color=3D#00ffff>);</FONT>       <FONT color=3D#bebebe># don't change =
position
</FONT><FONT color=3D#ffa500>die</FONT> <FONT color=3D#00cd00>"Couldn't =
sysseek: $!\n"</FONT> <FONT color=3D#ffa500>unless</FONT> <FONT =
color=3D#ff7f50>defined</FONT> $pos<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN433>Reading Lines with Continuation=20
Characters</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ff7f50>defined</FONT><FONT =
color=3D#00ffff>(</FONT>$line =3D &lt;FH&gt;<FONT =
color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>chomp</FONT> $line<FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ <FONT color=3D#ff7f50>s</FONT>/\\$//<FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>{</FONT>
        $line .=3D &lt;FH&gt;<FONT color=3D#00ffff>;</FONT>
        <FONT color=3D#ffa500>redo</FONT> <FONT =
color=3D#ffa500>unless</FONT> <FONT color=3D#98fb98>eof</FONT><FONT =
color=3D#00ffff>(</FONT>FH<FONT color=3D#00ffff>);</FONT>
    <FONT color=3D#00ffff>}</FONT>
    <FONT color=3D#bebebe># process full record in $line here
</FONT><FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
# DISTFILES =3D $(DIST_COMMON) $(SOURCES) $(HEADERS) \
#         $(TEXINFOS) $(INFOS) $(MANS) $(DATA)
# DEP_DISTFILES =3D $(DIST_COMMON) $(SOURCES) $(HEADERS) \
#         $(TEXINFOS) $(INFO_DEPS) $(MANS) $(DATA) \
#         $(EXTRA_DIST)
#-----------------------------
</FONT><FONT color=3D#ffa500>if</FONT> <FONT =
color=3D#00ffff>(</FONT>$line =3D~ <FONT =
color=3D#ff7f50>s</FONT>/\\\s*$//<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT><FONT color=3D#43cd80> </FONT>
    <FONT color=3D#bebebe># as before
</FONT><FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN436>Counting Lines (or Paragraphs or =
Records) in a=20
File</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT>$count =3D <FONT color=3D#00cd00>`wc -l &lt; $file`</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>die</FONT> <FONT color=3D#00cd00>"wc failed: =
$?"</FONT> <FONT color=3D#ffa500>if</FONT> $?<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ff7f50>chomp</FONT><FONT =
color=3D#00ffff>(</FONT>$count<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#98fb98>open</FONT><FONT =
color=3D#00ffff>(</FONT>FILE, <FONT color=3D#00cd00>"&lt; =
$file"</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> <FONT =
color=3D#00cd00>"can't open $file: $!"</FONT><FONT =
color=3D#00ffff>;</FONT>
$count++ <FONT color=3D#ffa500>while</FONT> &lt;FILE&gt;<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe># $count now holds the number of lines read
#-----------------------------
</FONT>$count +=3D <FONT color=3D#ff7f50>tr</FONT>/\n/\n/ <FONT =
color=3D#ffa500>while</FONT> <FONT color=3D#98fb98>sysread</FONT><FONT =
color=3D#00ffff>(</FONT>FILE, $_, <FONT color=3D#cdcd00>2</FONT> ** =
<FONT color=3D#cdcd00>16</FONT><FONT color=3D#00ffff>);</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#98fb98>open</FONT><FONT =
color=3D#00ffff>(</FONT>FILE, <FONT color=3D#00cd00>"&lt; =
$file"</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> <FONT =
color=3D#00cd00>"can't open $file: $!"</FONT><FONT =
color=3D#00ffff>;</FONT>
$count++ <FONT color=3D#ffa500>while</FONT> &lt;FILE&gt;<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe># $count now holds the number of lines read
#-----------------------------
</FONT><FONT color=3D#98fb98>open</FONT><FONT =
color=3D#00ffff>(</FONT>FILE, <FONT color=3D#00cd00>"&lt; =
$file"</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#98fb98>or</FONT> <FONT color=3D#ffa500>die</FONT> <FONT =
color=3D#00cd00>"can't open $file: $!"</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>for</FONT> <FONT =
color=3D#00ffff>(</FONT>$count=3D<FONT color=3D#cdcd00>0</FONT><FONT =
color=3D#00ffff>;</FONT> &lt;FILE&gt;<FONT color=3D#00ffff>;</FONT> =
$count++<FONT color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT> =
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#cdcd00>1</FONT> <FONT color=3D#ffa500>while</FONT> =
&lt;FILE&gt;<FONT color=3D#00ffff>;</FONT>
$count =3D $.<FONT color=3D#00ffff>;</FONT>
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