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Perl File Handling

Perl File Handling. FileHandle : Name for I/O connection STDIN, STDOUT, STDERR are given Other Files Open(FILEHANDLE, “somename”); FILEHANDLE is a name being used in Perl “somename” is a file name in OS Open(OUT, “>outfile”); Open(LOGFILE, “>>mylogfile”); Close(LOGFILE);.

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Perl File Handling

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  1. Perl File Handling • FileHandle : Name for I/O connection • STDIN, STDOUT, STDERR are given • Other Files • Open(FILEHANDLE, “somename”); • FILEHANDLE is a name being used in Perl • “somename” is a file name in OS • Open(OUT, “>outfile”); • Open(LOGFILE, “>>mylogfile”); • Close(LOGFILE);

  2. Input/Output to File open (FIL , “some-file”); while ( $_ = <FIL> ) { chop; print STDOUT “some-file has $_ !\n”; } close(FIL);

  3. Flat File Database • A text file database • Each line of the file is a new record in DB • The fields are separated by pipe symbol(|) • guestbook.dat Sunghun Park|sunghun.park@mail.utexas.edu|Testing Joe Smith|jsmith@mail.utexas.edu|Hello Everybody

  4. guestbrowse.cgi #!/usr/local/bin/perl require 'cgi-lib.pl'; # Include library + use it print "Content-type: text/html\n\n"; print "<HTML><h1>The Contents of Guestbook</h1>"; print "<TABLE BORDER=1>\n"; print "<TR><TD>Name of Guest</TD><TD>E-Mail</TD><TD>Comments from Guest</TD>\n"; open(GUESTBOOK,"guestbook.dat") || die "\n<H1>Can't Open Guestbook file!</H1>"; while (<GUESTBOOK>) { chop($_); ($name, $email, $comment) = split(/\|/, $_); print "<TR><TD> $name </TD><TD> <A HREF=\"mailto:$email\">$email </A></TD><TD>$comment </TD></TR>\n"; } print "</TABLE>\n"; close(GUESTBOOK);

  5. Split Function • Split takes a regular expression and a string • Split returns a list of values • $line = “C:\\;;C:\\Windows\\;”; • @fields = split(/;/, $line); • now $fields is (“C:\”, “”, “C:\Windows”) • @fields 는 첨자형 변수 전체를 지칭 • $fields[0], $fields[1], $fields[2]는 각각의 첨자형변수

  6. Perl 첨자형 변수(2가지) • 단순한 변수는 $x, $y • $days[28] 는 첨자형 변수 • $#days 는 @days의 마지막 첨자 값을 표시함 • $days[0], $days[1], $days[2], ….$days[$#days] • $days{‘Feb’} 는 associate array를 표시 • 전체는 %days로 표시한다 • (키값1, 값1, 키값2, 값2, ….) • $days{‘Jan’} 등으로 사용한다 • VB의 ReQuest.QueryString(“name”)등의 기능은 여기서 왔다 • foreach $i (keys %ENV) print “$i = $ENV{$i}”;

  7. guestentry.htm <HTML> …. <HR> <FORM ACTION="http://mis2.myngji.ac.kr/cgi-bin/cgiwrap/shpark/guestentry.cgi” METHOD=POST> <CENTER> <TABLE WIDTH=50%> <TR><TD ALIGN=RIGHT><B>Name:</B></TD><TD><INPUT TYPE=text NAME=name></TD></TR> <TR><TD ALIGN=RIGHT><B>E-Mail Address:</B></TD><TD><INPUT TYPE=text NAME=email></TD></TR> <TR><TD ALIGN=RIGHT><B>Short Comment:</B></TD><TD><INPUT TYPE=text NAME=comment></TD></TR> <TR><TD></TD><TD><INPUT TYPE=submit VALUE="Submit To Guestbook"></TD></TR> </TABLE> </CENTER> </FORM> …</HTML>

  8. guestentry.cgi #!/usr/local/bin/perl require "cgi-lib.pl"; # Include library + use it &ReadParse(*input); print STDOUT "Content-type: text/html\n\n"; print STDOUT "<HTML>\n"; open(GUESTBOOK,">>guestbook.dat") || die "<H2>Can't Open Guestbook file!</H2>"; if ( $input{'name'} NE "" ) { print GUESTBOOK "$input{'name'}|$input{'email'}|$input{comment}\n"; print STDOUT "<center>$input{'name'}<p>\n"; print STDOUT "$input{'email'}<p>\n"; print STDOUT "$input{'comment'}<p>\n"; print STDOUT "Added to the Guestbook<p>\n"; } else { print STDOUT "<H2>Please enter at least your name!!</h2>\n"; } close(GUESTBOOK);

  9. cgi-lib.pl • Old Perl module(library) for handling CGI stuffs • New version is CGI.pm • After calling &ReadParse(*input); • &… 는 부프로그램 …를 호출하는 방식 • *input 은 첨자형 변수 %input을 인수로 넘겨줌 • $ENV{…} 환경변수들이 제공된다 • “REQUEST_METHOD”, “CONTENT_LENGTH” • $ENV{‘REQUEST_METHOD’} • $input{…} Form변수들이 제공된다 • “name”, “email” 등은 Form에서 사용한 필드명들 • $input{‘name’}, $input{‘email’}등은 사용자가 입력한 값을 저장하고 있다

  10. Searching in Perl I • Powerful pattern matching with regular expression to a string • More general than wild card file or dir name • while (<>) { • if ( /ab*c/ ) { • print $_; • } } • substitue operator • s/abc*c/def/;

  11. Searching in Perl II • If pattern to search is not in $_, use =~ • $a = “hello world”; • $a =~ /^he/; • $a =~ /$b/i

  12. guestsearch.cgi #!/usr/local/bin/perl require 'cgi-lib.pl';# Include library + use it &ReadParse(*input); print "Content-type: text/html\n\n"; print "<HTML><h1>The Messages from Guest $input{'name'}</h1>"; print "<TABLE BORDER=1>\n"; print "<TR><TD>Name of Guest</TD><TD>E-Mail</TD><TD>Comments from Guest</TD>\n"; open(GUESTBOOK,"guestbook.dat") || die "\n<H1>Can't Open Guestbook file!</H1>"; while (<GUESTBOOK>) { chop($_); ($name, $email, $comment) = split(/\|/, $_); if ( $name =~ /$input{'name'}/i ) { print "<TR><TD> $name </TD><TD> <A HREF=\"mailto:$email\">$email </A></TD><TD>$comment </TD></TR>\n"; } } print "</TABLE>\n"; close(GUESTBOOK);

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