use Modern::Perl;

say map {(split)[1]} <DATA>;

__DATA__
IF-abc/12 [Se/0/0] [Second data][third]
IF-abc/1 [Gi/0/0] [Second data ]

##</code><code>##

[Se/0/0][Gi/0/0]

##</code><code>##

say /(\[.*?\])/ while <DATA>;

##</code><code>##

[Se/0/0]
[Gi/0/0]