On 07Jun2007 07:25, abhishek misra <[EMAIL PROTECTED]> wrote: | elm3a138:/dev # ls | grep std | stderr | stdin | stdout | elm3a138:/dev #
Try this: ls -ld /dev/std* It is more informative. | does a linux system have single set of std files or does every program has a set of its own. Every program has its own. And when you talk about them in this case, you are _not_ talking about the files in /dev. Every program has assorted open files; each open file is identified to the program with a "file descriptor", a number starting at 0. Descriptor zero is stdin, descriptor 1 is stdout and descriptor 2 is stderr. Other open files will have other descriptor numbers. In /dev/fd (a directory) are a bunch of special files named numericly: ls /dev/fd Like /dev/tty, which when opened gives you a file handle attached to your terminal, opening /dev/fd/n (where 'n' is a number) gives you a file handle attached to the same file as file descriptor 'n' in your current process. /dev/stdin, stdout and stderr are convenient symbolic links to /dev/fd/0, 1, and 2. That is all. No magic. | it is also said that as every program starts it is supplied these files Yes. | when we run different progs on different terminals, each of them has its i/o on that terminal only Yes. | so i think that every one gets their own set Yes. | but then it does not make sence for /dev to have these listed There are various programs that can only be handed filenames when run. For such programs is it convenient to have "filenames" that will open a process' already-open files. So you might use the filename /dev/fd/1 to has - as a filename - your current stnadard output to a command as a filename argument. | are file discriptors unique to the system or the process The process. Each descriptor is an index into a per-process table of open files. At the OS level, to write to a file you issue a function call like: write(fd, buffer, size) where fd is the fiel descriptor - of course the file is open by the time you write to it; in fact it must be open - there is no other way to try to write. -- Cameron Simpson <[EMAIL PROTECTED]> DoD#743 http://www.cskk.ezoshosting.com/cs/ The mystery is why a proud people, descended from revolutionaries, is willing to submit, with good humor, to the intrusion of corporate and governmental authorities. - Barbara Ehrenreich To unsubscribe from this list, please email [EMAIL PROTECTED] & you will be removed. Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/LINUX_Newbies/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/LINUX_Newbies/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
