Just Another Polyglot Hacker!
C, C++, Perl, Bash – 230
#include &lt;stdio.h&gt;
#define c const char*\
s=&quot;just another %s hacker\n&quot;
//bin/test;printf &quot;$s&quot; Bash;exit
int main(){c;printf(s,sizeof'a'-1?&quot;C&quot;:&quot;C++&quot;);}
/*==;seek DATA,0,0;@a=readline DATA;eval'$'.$a[2];printf $s,&quot;Perl&quot;;
__DATA__*/

This was fun! :-)
230 chars including a newline at end of file. To run, save as both poly.c and poly.cpp and do:
$ gcc -Wall -Wextra -pedantic poly.c &amp;&amp; ./a.out 
just another C hacker
$ g++ -Wall -Wextra -pedantic poly.cpp &amp;&amp; ./a.out 
just another C++ hacker
$ perl poly.c
just another Perl hacker
$ bash poly.c
just another Bash hacker