exp EXPR exp Returns e (the natural logarithm base) to the power of EXPR. If EXPR is omitted, gives exp($_).

exit EXPR exit Evaluates EXPR and exits immediately with that value. Example: $ans = <STDIN>; exit 0 if $ans =~ /^[Xx]/; See also die. If EXPR is omitted, exits with 0 status. The only universally recognized values for EXPR are 0 for success and 1 for error; other values are subject to interpretation depending on the environment in which the Perl program is running. For example, exiting 69 (EX_UNAVAILABLE) from a sendmail incoming-mail filter will cause the mailer to return the item unde

exists EXPR Given an expression that specifies an element of a hash, returns true if the specified element in the hash has ever been initialized, even if the corresponding value is undefined. print "Exists\n" if exists $hash{$key}; print "Defined\n" if defined $hash{$key}; print "True\n" if $hash{$key}; exists may also be called on array elements, but its behavior is much less obvious and is strongly tied to the use of delete on arrays. WARNING: Calling exists on array values is stro

exec LIST exec PROGRAM LIST The exec function executes a system command and never returns; use system instead of exec if you want it to return. It fails and returns false only if the command does not exist and it is executed directly instead of via your system's command shell (see below). Since it's a common mistake to use exec instead of system, Perl warns you if exec is called in void context and if there is a following statement that isn't die, warn, or exit (if -w is set--but you always do

evalbytes EXPR evalbytes This function is like eval with a string argument, except it always parses its argument, or $_ if EXPR is omitted, as a string of bytes. A string containing characters whose ordinal value exceeds 255 results in an error. Source filters activated within the evaluated code apply to the code itself. This function is only available under the evalbytes feature, a use v5.16 (or higher) declaration, or with a CORE:: prefix. See feature for more information.

eval EXPR eval BLOCK eval In the first form, often referred to as a "string eval", the return value of EXPR is parsed and executed as if it were a little Perl program. The value of the expression (which is itself determined within scalar context) is first parsed, and if there were no errors, executed as a block within the lexical context of the current Perl program. This means, that in particular, any outer lexical variables are visible to it, and any package variable settings or subroutine and

NAME SYNOPSIS DESCRIPTION CAVEATS AUTHOR COPYRIGHT NAME Errno - System errno constants SYNOPSIS use Errno qw(EINTR EIO :POSIX); DESCRIPTION Errno defines and conditionally exports all the error constants defined in your system errno.h include file. It has a single export tag, :POSIX , which will export all POSIX defined error numbers. Errno also makes %! magic such that each element of %! has a non-zero value only if $! is set to that value. For example: use Errno; unless (open(FH, "/fangor

Equality Operators Binary "==" returns true if the left argument is numerically equal to the right argument. Binary "!=" returns true if the left argument is numerically not equal to the right argument. Binary "<=>" returns -1, 0, or 1 depending on whether the left argument is numerically less than, equal to, or greater than the right argument. If your platform supports NaN 's (not-a-numbers) as numeric values, using them with "<=>" returns undef. NaN is not "<" , "==" , ">

eq These operators are documented in perlop.

eof FILEHANDLE eof () eof Returns 1 if the next read on FILEHANDLE will return end of file or if FILEHANDLE is not open. FILEHANDLE may be an expression whose value gives the real filehandle. (Note that this function actually reads a character and then ungetc s it, so isn't useful in an interactive context.) Do not read from a terminal file (or call eof(FILEHANDLE) on it) after end-of-file is reached. File types such as terminals may lose the end-of-file condition if you do. An eof without an a