mkdir limitations Post: 26918

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Top Forums UNIX for Dummies Questions & Answers mkdir limitations Post 26918 by Perderabo on Monday 26th of August 2002 08:20:52 AM

08-26-2002

Administrator Emeritus

I did a "man mkdir" and I didn't find an answer to these questions.

The mkdir() system call code in the kernel does not directly impose a limit on the length of a filename. However it must talk to the code for filesystem and this will impose a limit. What that limit is depends on the file system. Posix will guarantee at least 14 characters. To be posix compliant, a unix system must allow at least that much. HP-UX still supports the "short filename" option. If you choose, you can make HP-UX enforce a 14 character limit. This is rarely done. The most common limit these days is 255 characters for a filename. And the most common limit for a full path name is 1023.

You probably will find that you have a pathconf() system call that can determine your exact limit. Note that you must give pathconf() a file name because the limits can vary from filesystem to filesystem.

Because a slash is used to separate the components of a pathname, a slash cannot be used inside a component. And binary zero is used to terminate a string. So no binary zeros either. Any other byte value is fair game as far as the kernel is concerned. A filename with an embedded carriage return will cause you nasty problems. And you really will be better off if you limit yourself to printable characters.

Perderabo

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qpsmtpd-forkserver

qpsmtpd-forkserver(8)					      System Manager's Manual					     qpsmtpd-forkserver(8)

NAME

       qpsmtpd-forkserver - Fork-on-demand server for qpsmtpd

SYNOPSIS

       qpsmtpd-forkserver [options]

DESCRIPTION

       qpsmtpd-forkserver is the qpsmtpd frontend script which binds to the SMTP TCP socket and forks as clients connect.

OPTIONS

       --port port, -p port
	      Binds to a specific port, instead of the default 2525.

       --user user, -u user
	      On  startup,  switch to run as user instead of the starting user.  Applies only when started as root (as is normal when listening on
	      port 25).

       --limit-connections limit, -c limit
	      Accept at most limit simultaneous connections.  Inbound connections beyondthis limit will be deferred or refused.

       --max-from-ip limit, -m limit
	      Accept at most limit simultaneous connections from any given IP address; does not override --limit-connections, if set.

       --listen-address addr, -l addr
	      Bind to the local address addr, instead of the default behavior of binding to all interfaces.  Can be specified  multiple  times	to
	      bind to more than one interface or local address.

       --detach, -d
	      Detach from the controlling terminal at startup, to run as a standalone daemon.  See also --pid-file.

       --pid-file filename
	      Upon  startup, and after daemonizing if applicable, write the process ID to filename, for use by sysvinit control scripts or similar
	      utilities.

AUTHOR

       Ask Bjorn Hansen <ask@develooper.com>
       http://smtpd.develooper.com/

															     qpsmtpd-forkserver(8)

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