my $previous_default = select ( STDOUT ) # save previous default.Standard output and standard error for instance, you have to unbufferĮach (although STDERR might be unbuffered by default): Is one of the per-filehandle special variables, so eachįilehandle has its own copy of its value. (mnemonic: making your filehandles "piping hot"): To get around this, you have to unbuffer the output filehandle, in this # long wait, then row of dots all at once.Have a long wait before you see a row of 50 dots all at once: Instead of seeing a dot for every line, Perl buffers the output and you Screen for every line you process to watch the progress of your program. By saving up output, it makes fewer expensive system calls.įor instance, in this little bit of code, you want to print a dot to the Perl normally buffers output so it doesn't make a system call for everyīit of output. You might like to read Mark Jason Dominus's "Suffering From Buffering" How do I flush/unbuffer an output filehandle? Why must I do this? This section deals with I/O and the "f" issues: filehandles, flushing,įormats, and footers. Why do I get weird spaces when I print an array of lines?.How do I select a random line from a file?.Why does Perl let me delete read-only files? Why does -i clobber protected files? Isn't this a bug in Perl?.Why doesn't glob("*.*") get all the files?.Why can't I use "C:\temp\foo" in DOS paths? Why doesn't `C:\temp\foo.exe` work?.How do I close a file descriptor by number?.How can I tell whether there's a character waiting on a filehandle?.How can I read a single character from a file? From the keyboard?.How can I read in a file by paragraphs?.How can I read in an entire file all at once?.How do I print to more than one file at once?.How do I set a file's timestamp in perl?.How do I get a file's timestamp in perl?.How do I randomly update a binary file?.All I want to do is append a small amount of text to the end of a file.I just want to increment the number in the file. Why can't I just open(FH, ">file.lock")?. How can I open a file with a leading ">" or trailing blanks?.Why do I sometimes get an "Argument list too long" when I use ?.How come when I open a file read-write it wipes it out?.How can I translate tildes (~) in a filename?.How can I output my numbers with commas added?.How can I open a filehandle to a string?.How can I set up a footer format to be used with write()?.How can I make a filehandle local to a subroutine? How do I pass filehandles between subroutines? How do I make an array of filehandles?.
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