One liner is returning unexpected "1" on the output and I do not understand the mechanism at play.

[perlynewby]

I am getting an unexpected output from a one-liner and I do not understand what it is I am doing wrong. the one-liner is outputting a "1" before the line number. I've tried to simplify the one-liner to try to understand the output but still eludes me but, maybe, someone here can part with some of the wisdom.

____data.txt____

name = Leah last_name = Pellegrini age = 32 profession = "artist" / "e
+ngineer of all things" favorite_song = "I'm alive" performer = "Micha
+el Franti"
     name = alberto last_name = Montelongo age = 32 profession = "cool
+ dude" favorite_song = "#41" performeer = "DMB"

Name = Lucca last_name = montelongo age = 6 profession = "future Blue 
+Angel" favorite-song = "sunflower" performer = "Post Malone"
                  Name = josh  last_name = montelongo age = 26 profess
+ion = "happy" favorite-song = "satellite" performer = "dmb"

Name = josh  last_name = montelongo age = 26 profession = "happy" favo
+rite-song = "satellite" performer = "dmb"

1) One-liner seeking to build up to do multiple things like only print odd lines, print lines with text only, OR print if regexp match. Then print line with no leading space, number of the lines, space out with a \tab.

 perl -lane 'print s/^\s+//,$., "\t", @F[0,1,2,],"\t",@F[3,4,5], if (($.%2) && /\w+/ || /cool dude/)' data.txt

13      name=alberto    last_name=Monte
5       Name=Lucca      last_name=monte

Please, notice the 1 before the odd line number 3, Why is that? Is my substitution not written correctly? I am replacing the space with no space. If I remove this substitution the output is fine but it is unexpected to me and I cannot understand the mechanism that is at work here with this substitution.

2) Now, the same one-liner but printing the even lines.

perl -lane 'print s/^\s+//,$., "\t", @F[0,1,2,],"\t",@F[3,4,5], if (($.%2==0) && /\w+/ || /cool dude/)' data.txt

2       name=Marta      last_name=Pellegrini
13      name=alberto    last_name=Monte
16      Name=josh       last_name=monte
8       Name=josh       last_name=monte

This is to illustrate the susbtitution in line 3 (satisfies OR condition) and 6(even lines). I'll appreciate and explanation why the substitution is outputing these ones.

Additional challenge: count the repeating names in the data.txt. I did a ~tr/=// as a character count but unable to think of a counter for "name" to add to this one-liner ;-)

[choroba]

As documented in perlop, the substitution

> Searches a string for a pattern, and if found, replaces that pattern with the replacement text and returns the number of substitutions made.

Your s/// replaced once, so it returned 1. Run the substitution before printing the result.

[perlynewby]

Yes, this is what I did not understand that replacing the space to no space would return 1. I went I did a few experiments to solidify my understanding. I spent so much time reading but could not understand the inner workings; I appreciate it so much.

[haukex]

Maybe this table of the return values of regular expressions can be helpful as well.

[ikegami]

Run the substitution before printing the result.

...or use s///r

[Anonymous Monk]

...or use s///r

not what OP wants