in reply to One-liner to append text at fixed column

Fiddling around a bit, trying to find a solution where it becomes more clear what is being searched for and which characters are being replaced. But still, it is not very pretty.

$_ = "abc_something" ;
print $_ . "\n" if /abc/ &&
   substr(  $_, 0, 4 ) =~ s/(.+)/" "x((length $1)+2)."#:"/e ;

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The substr just takes care of replacing the first part with "      #:". Make sure that the search for 'abc' is done before doing the replacement since it is greedy.

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Re^2: One-liner to append text at fixed column
by LanX (Saint) on Nov 16, 2018 at 13:29 UTC
    If it comes to readability I prefer my last sprintf solution with the twist of changing if to and .

    perl -lpe " /(match1|match2)/ and $_ = sprintf qq{%-68s  #$1}, $_ "

    Normally I don't like short-circuit expressions, but in this case it really helps clarifying what's happening.

    Demo: (win quoting)

    >perl -E"say '.' x rand(80) for 1..10" |perl -lpe " /(.)/ and $_ = spr
+intf qq{%-68s  #$1},$_ "
......................................................................
+......  #.
......................                                                
+#.
.....................                                                 
+#.
......................................................................
+....  #.
.........................................................             
+#.
......................................                                
+#.
.........................                                             
+#.
........................................................              
+#.
......................................................................
+...  #.
.........................                                             
+#.

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    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

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      Ok, I think I did not understand the original problem. I thought you were trying to 'align' all the comments from a text like this:

      perl -E"say '.' x rand(80) . '# test comment' for 1..3"
......................# test comment
.................................# test comment
......................................................................
+....# test comment

      [download]

      So eventually I came up with this which I think is too complex. 

      perl -E"say '.' x rand(80) . '# test comment' for 1..10" |perl -lpe " 
+/\s*#(.*)$|$/ && ( substr(  $_, $-[0], length($_) ) = qq{ }x(68 - $-[
+0] + 2) . qq{ #$1} )
...............................................                       
+ # test comment
..........................................................            
+ # test comment
.......................................                               
+ # test comment
............................................................          
+ # test comment
......................................................................
+.... # test comment
......                                                                
+ # test comment
........................................                              
+ # test comment
...............................                                       
+ # test comment
...................................................                   
+ # test comment
...................................                                   
+ # test comment

      [download]

      Maybe it can be rewritten with a printf but I will leave it with this.

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        > I thought you were trying to align all the comments from a text like this:

        Oh in this case I'd use the same "match-and-printf" construct, it's extremely flexible.

        D:\tmp>perl -E"say '.' x rand(70) . '# test comment' for 1..3"
....................# test comment
...................................# test comment
.......................# test comment

D:\tmp>perl -E"say '.' x rand(70) . '# test comment' for 1..20" |perl 
+-lpe " /(.*?)(#.*)/ and $_ = sprintf qq{%-68s  %s},$1,$2"
.....................                                                 
+# test comment
..............................................................        
+# test comment
..................................................................... 
+ # test comment
....................................                                  
+# test comment
..........................................................            
+# test comment
...............................................                       
+# test comment
............................................................          
+# test comment
.............                                                         
+# test comment
...........................                                           
+# test comment
...............                                                       
+# test comment
..............................                                        
+# test comment
....................................                                  
+# test comment
...................................................                   
+# test comment
.................................                                     
+# test comment
...........................................................           
+# test comment
..........                                                            
+# test comment
.......................................................               
+# test comment
.................................................................     
+# test comment
..........................................                            
+# test comment
................................................................      
+# test comment

        [download]

        Cheers Rolf
        (addicted to the Perl Programming Language :)
        Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

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