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Re^3: System command using array and pipe

by philipbailey (Chaplain)
on Jun 05, 2011 at 09:12 UTC ( #908176=note: print w/ replies, xml ) Need Help??


in reply to Re^2: System command using array and pipe
in thread System command using array and pipe

Your comments are fair, but in common use cases appropriate quoting of the shell command line is sufficient, especially if one can control the contents of the password and filename. If these come from arbitrary user input, then your approach is more reasonable.


Comment on Re^3: System command using array and pipe
Re^4: System command using array and pipe
by ikegami (Pope) on Jun 06, 2011 at 18:17 UTC
    I'm not sure what you mean. I can guess you'd mean one of these.
    • Store the shell literal in the config.

      my $password = '...'; # Not the password, but a shell literal of the +password. system( ... "-p$password" ... );
    • Pretend the config is a shell literal.

      my $password = '...'; system( ... "-p$password" ... ); # Pretend $password is a shell liter +al.
    • Embed the config data in the command

      system( ... "-p..." ... );

    Every one of these are very unappealing to me.

      The only issue that cannot be resolved by single quoting relevant parts of the command line is of escaping single quotes. Either do this manually, or do something simple like this:

      s#'#'\\''#g for ($password, $path); system("mysqldump --add-drop-table -uroot -p'$password' mydatabase | g +zip -9c > '$path'");

      Update: s/// command corrected as per ikegami.

        I prefer
        my ($passwd_lit, $path_lit) = map text_to_shell_lit, $passwd, $path; system("mysqldump --add-drop-table -uroot -p$passwd_lit mydatabase | g +zip -9c > $path_lit");
        to
        my $passwd_lit = $passwd; my $path_lit = $path; s#'#'\\''#g for $passwd_lit, $path_lit; system("mysqldump --add-drop-table -uroot -p'$passwd_lit' mydatabase | + gzip -9c > '$path_lit'");

        but to each his own.

        By the way, your quoting was buggy. "\" is not special in sh single-quoted literals.

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