See wantarray for more on how the evaluation context can be determined.
The blocks on your disk are probably about 8K bytes, and your computer hardware is probably designed to transfer an entire block of data from the disk at once. It used to report whether memory for that aggregate had ever been allocated.Older implementations of crypt only needed the first two characters of the SALT, but code that only gives the first two characters is now considered nonportable. The single-argument form turns on binary mode. In scalar context, this means that you get the value of the last element deleted or the undefined value if that element did not exist. See the perlsub manpage. This makes any input operation return immediately if nothing is available when reading from a pipe, socket, or serial line that would otherwise block. See the precedence table in perlop. The block of evalBLOCK does not count as a loop, so the loop control statements next, last, or redo cannot be used to leave or restart the block.
The latter is part of Perl's report formatting package, which we won't discuss further. Choices are shown here. For alarms of finer granularity than one second, you might be able to use the syscall function to access setitimer 2 if your system supports it.It doesn't matter whether the corresponding value is true or false, or whether the value is even defined. This makes any input operation return immediately if nothing is available when reading from a pipe, socket, or serial line that would otherwise block. So to make them distinct, Perl programmers often represent them in all capital letters, or caps. Then it stores this block of data in a region of memory that is called a buffer, and gives you back the one line you asked for. Only one timer may be active at once. If you add or delete elements of a hash while you're iterating over it, the resulting behavior is not well-defined: entries might get skipped or duplicated. If you add or delete elements of a hash while you're iterating over it, you may get entries skipped or duplicated, so don't. The first element of the list must be the numerical mode, as in the chmod 2 syscall. If you somehow manage to reap an exited pipe child on your own, the close will fail. This allows your code to work with the standard crypt and with more exotic implementations. The exec call and system, too will not distinguish between a single scalar argument and an array containing only one element. Whichever form you use, eval is the preferred way to do all exception handling in Perl. It used to report whether memory for that aggregate had ever been allocated. Use of defined on aggregates hashes and arrays is deprecated. Since Perl 5.
DBM stands for database management, and consists of a set of C library routines that allow random access to records via a hashing algorithm.
The second form compiles and executes little bits of code on the fly at run time, and also conveniently traps any exceptions just like the first form.
The fcntl function will raise an exception if used on a system that doesn't implement fcntl 2. When you write data to a file with print, the data doesn't normally go into the file right away.