Could try this too
perl -p -i.bak -e '/^ftp/ ? undef $_ : s/\bguest\b/ftp/gi' /etc/passwd
the -i.bak will also create a /etc/passwd.bak for you
Timothy Johnson wrote:
>
> Actually it's a good question, and I should have explained myself. When you
> do this line on a file, it slurps up the entire contents of the file into an
> array:
>
> @infile = <INFILE>;
>
> So the way to read a huge file without loading the entire file into memory
> is to use a while loop:
>
> but this changes the way you go about this a little bit. The code becomes:
>
> ##############################
>
> open(INFILE,"/etc/passwd");
> open(OUTFILE,">/etc/passwd.bak"); #open a temp file to write
>
> while(<INFILE>){ #loads each line into $_, one line per loop
> if($_ =~ /^ftp/i){ #if it starts with "ftp"
> $_ = ''; #make it a zero-length string
> }elsif($_ =~ /guest/i){ #else if it contains "guest"
> $_ =~ s/guest/ftp/gi;#replace it with "ftp"
> }
> print OUTFILE $_; #write the changed code to the temp file
> }
>
> open(INFILE,"/etc/passwd.bak"); #now we copy the contents of
> open(OUTFILE,">/etc/passwd"); #the temp file to the original
> while(<INFILE>){
> print OUTFILE $_;
> }
> close INFILE;
> close OUTFILE;
> unlink "/etc/passwd.bak"; #remove the temp file
>
> ######################
>
> So the one real difference is that instead of creating a copy in memory, we
> have to create a temporary file to hold the contents of our changes.
>
> -----Original Message-----
> From: Langa Kentane
> To: 'Timothy Johnson'
> Sent: 5/13/02 10:54 PM
> Subject: RE: Delete a line and replace
>
> Hi
> Just a quick newbie question:
> How would you recommend we do that on a big file?
>
> -----Original Message-----
> From: Timothy Johnson [mailto:[EMAIL PROTECTED]]
> Sent: 13 May 2002 08:05 PM
> To: 'Jorge Goncalvez'; [EMAIL PROTECTED]
> Subject: RE: Delete a line and replace
>
> You can try something like this:
>
> open(INFILE,"/etc/passwd");
> @infile = <INFILE>; #don't do this if your file gets big
> close INFILE;
>
> foreach(@infile){
> if($_ =~ /^ftp/i){ #if it starts with "ftp"
> $_ = ''; #make it a zero-length string
> }elsif($_ =~ /guest/i){ #else if it contains "guest"
> $_ =~ s/guest/ftp/gi;#replace it with "ftp"
> }
> }
>
> open(OUTFILE,">/etc/passwd");
> print OUTFILE @infile;
>
> -----Original Message-----
> From: Jorge Goncalvez [mailto:[EMAIL PROTECTED]]
> Sent: Monday, May 13, 2002 1:41 AM
> To: [EMAIL PROTECTED]
> Subject: Re:Delete a line and replace
>
> Hi, i have this file /etc/passwd like this:
>
> Everyone:*:0:0:,S-1-1-0::
> SYSTEM:*:18:18:,S-1-5-18::
> Administrators:*:544:544:,S-1-5-32-544::
> Administrator:unused_by_nt/2000/xp:500:513:U-LININF54\Administrator,S-1-
> 5-21
> -175 7981266-2139871995-725345543-500:/home/Administrator:/bin/bash
> anonymous:unused_by_nt/2000/xp:1017:513:U-LININF54\anonymous,S-1-5-21-17
> 5798
> 1266
> -2139871995-725345543-1017:/home/anonymous:/bin/bash
> ftp:unused_by_nt/2000/xp:1018:513:U-LININF54\ftp,S-1-5-21-1757981266-213
> 9871
> 995-
> 725345543-1018:/:/bin/bash
> Guest:unused_by_nt/2000/xp:501:513:U-LININF54\Guest,S-1-5-21-1757981266-
> 2139
> 8719
> 95-725345543-501:/home/Guest:/bin/bash
> HelpAssistant:unused_by_nt/2000/xp:1000:513:Remote Desktop Help
> Assistant
> Account,U-LININF54\HelpAssistant,S-1-5-21-1757981266-2139871995-72534554
> 3-10
> 00:/
> home/HelpAssistant:/bin/bash
>
> I wanted to delete all the line which begins with ftp and then replace
> Guest
> by
> ftp in all file.
>
> Thanks.
>
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