comment on

But, when you use those functions, it will be executed by the shell, and the value will be returned.

Really?

q:~ [10:07:26]$ ps U blazar
  PID TTY      STAT   TIME COMMAND
11831 ?        S      0:00 sshd: blazar@pts/0
11838 pts/0    Ss     0:00 -bash
11857 pts/0    R+     0:00 ps U blazar
q:~ [10:07:32]$ perl -e 'system qw/sleep 600/'

[1]+  Stopped                 perl -e 'system qw/sleep 600/'
q:~ [10:08:09]$ ps U blazar
  PID TTY      STAT   TIME COMMAND
11831 ?        S      0:00 sshd: blazar@pts/0
11838 pts/0    Ss     0:00 -bash
11908 pts/0    T      0:00 perl -e system qw/sleep 600/
11909 pts/0    T      0:00 sleep 600
11922 pts/0    R+     0:00 ps U blazar
[download]

I don't see additional shells...

(To the benefit of the OP) this "detail" apart, indeed system calls are expensive.

In reply to Re^2: comparison between system operators and Built in function by blazar
in thread comparison between system operators and Built in function by jesuashok

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


more useful options
	PerlMonks