如何解决此匹配问题并替换Perl文件中仅单词的第n个出现的问题

Question

Suppose I have a file which has these few lines

Hello abc
hii
how are you
Hello abc

If I want to replace the 2nd occurrence of abc by xyz, how can I do?

I want an output like

Hello abc
hii
how are you
Hello xyz

I tried doing perl -pi -e 's/abc/xyz/ if $. == 2' filename perl -pi -e 's/abc/xyz/ if $. == 2' filename . It is not working for me. Can anyone help me with this?

Answer 1

perl -i -pe's/abc/ ++$count == 2 ? "xyz" : "abc" /eg' file

即使abc每行显示多次，此方法也有效。

Answer 2

计算abc出现的时间，如果等于2，则替换为2：

perl -i -pe'$found++ if /abc/; s/abc/xyz/ if $found ==2' filename

Answer 3

I have done it as a script. The first argument is the pattern, the second the replacement, the third the number of repetitions and the forth the file, you can also omit the file and insert the data vía stdin.

#!/usr/bin/env perl
use v5.28;
my $patt = shift;
my $rep = shift;
my $nth = shift;
my $reps = 0;
while (<>) {
    $reps++ if /$patt/;
    s/$patt/$rep/ if (/$patt/ && $reps == $nth);
    print $_;
}