857 lines
43 KiB
Groff
857 lines
43 KiB
Groff
.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
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.\"
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.\" Standard preamble:
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.\" ========================================================================
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.\" Set up some character translations and predefined strings. \*(-- will
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.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
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.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
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.\" ========================================================================
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.\"
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.IX Title "PERLFUNC 1"
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.TH PERLFUNC 1 "2006-01-07" "perl v5.8.8" "Perl Programmers Reference Guide"
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.SH "NAME"
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.IX Xref "function"
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perlfunc \- Perl builtin functions
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.SH "DESCRIPTION"
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.IX Header "DESCRIPTION"
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The functions in this section can serve as terms in an expression.
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They fall into two major categories: list operators and named unary
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operators. These differ in their precedence relationship with a
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following comma. (See the precedence table in perlop.) List
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operators take more than one argument, while unary operators can never
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take more than one argument. Thus, a comma terminates the argument of
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a unary operator, but merely separates the arguments of a list
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operator. A unary operator generally provides a scalar context to its
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argument, while a list operator may provide either scalar or list
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contexts for its arguments. If it does both, the scalar arguments will
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be first, and the list argument will follow. (Note that there can ever
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be only one such list argument.) For instance, \fIsplice()\fR has three scalar
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arguments followed by a list, whereas \fIgethostbyname()\fR has four scalar
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arguments.
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.PP
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In the syntax descriptions that follow, list operators that expect a
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list (and provide list context for the elements of the list) are shown
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with \s-1LIST\s0 as an argument. Such a list may consist of any combination
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of scalar arguments or list values; the list values will be included
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in the list as if each individual element were interpolated at that
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point in the list, forming a longer single-dimensional list value.
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Commas should separate elements of the \s-1LIST\s0.
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.PP
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Any function in the list below may be used either with or without
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parentheses around its arguments. (The syntax descriptions omit the
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parentheses.) If you use the parentheses, the simple (but occasionally
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surprising) rule is this: It \fIlooks\fR like a function, therefore it \fIis\fR a
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function, and precedence doesn't matter. Otherwise it's a list
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operator or unary operator, and precedence does matter. And whitespace
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between the function and left parenthesis doesn't count\*(--so you need to
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be careful sometimes:
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.PP
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.Vb 5
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\& print 1+2+4; # Prints 7.
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\& print(1+2) + 4; # Prints 3.
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\& print (1+2)+4; # Also prints 3!
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\& print +(1+2)+4; # Prints 7.
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\& print ((1+2)+4); # Prints 7.
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.Ve
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.PP
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If you run Perl with the \fB\-w\fR switch it can warn you about this. For
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example, the third line above produces:
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.PP
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.Vb 2
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\& print (...) interpreted as function at - line 1.
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\& Useless use of integer addition in void context at - line 1.
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.Ve
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.PP
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A few functions take no arguments at all, and therefore work as neither
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unary nor list operators. These include such functions as \f(CW\*(C`time\*(C'\fR
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and \f(CW\*(C`endpwent\*(C'\fR. For example, \f(CW\*(C`time+86_400\*(C'\fR always means
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\&\f(CW\*(C`time() + 86_400\*(C'\fR.
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.PP
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For functions that can be used in either a scalar or list context,
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nonabortive failure is generally indicated in a scalar context by
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returning the undefined value, and in a list context by returning the
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null list.
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.PP
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Remember the following important rule: There is \fBno rule\fR that relates
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the behavior of an expression in list context to its behavior in scalar
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context, or vice versa. It might do two totally different things.
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Each operator and function decides which sort of value it would be most
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appropriate to return in scalar context. Some operators return the
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length of the list that would have been returned in list context. Some
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operators return the first value in the list. Some operators return the
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last value in the list. Some operators return a count of successful
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operations. In general, they do what you want, unless you want
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consistency.
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.IX Xref "context"
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.PP
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A named array in scalar context is quite different from what would at
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first glance appear to be a list in scalar context. You can't get a list
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like \f(CW\*(C`(1,2,3)\*(C'\fR into being in scalar context, because the compiler knows
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the context at compile time. It would generate the scalar comma operator
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there, not the list construction version of the comma. That means it
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was never a list to start with.
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.PP
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In general, functions in Perl that serve as wrappers for system calls
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of the same name (like \fIchown\fR\|(2), \fIfork\fR\|(2), \fIclosedir\fR\|(2), etc.) all return
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true when they succeed and \f(CW\*(C`undef\*(C'\fR otherwise, as is usually mentioned
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in the descriptions below. This is different from the C interfaces,
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which return \f(CW\*(C`\-1\*(C'\fR on failure. Exceptions to this rule are \f(CW\*(C`wait\*(C'\fR,
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\&\f(CW\*(C`waitpid\*(C'\fR, and \f(CW\*(C`syscall\*(C'\fR. System calls also set the special \f(CW$!\fR
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variable on failure. Other functions do not, except accidentally.
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.Sh "Perl Functions by Category"
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.IX Xref "function"
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.IX Subsection "Perl Functions by Category"
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Here are Perl's functions (including things that look like
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functions, like some keywords and named operators)
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arranged by category. Some functions appear in more
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than one place.
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.IP "Functions for SCALARs or strings" 4
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.IX Xref "scalar string character"
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.IX Item "Functions for SCALARs or strings"
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\&\f(CW\*(C`chomp\*(C'\fR, \f(CW\*(C`chop\*(C'\fR, \f(CW\*(C`chr\*(C'\fR, \f(CW\*(C`crypt\*(C'\fR, \f(CW\*(C`hex\*(C'\fR, \f(CW\*(C`index\*(C'\fR, \f(CW\*(C`lc\*(C'\fR, \f(CW\*(C`lcfirst\*(C'\fR,
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\&\f(CW\*(C`length\*(C'\fR, \f(CW\*(C`oct\*(C'\fR, \f(CW\*(C`ord\*(C'\fR, \f(CW\*(C`pack\*(C'\fR, \f(CW\*(C`q/STRING/\*(C'\fR, \f(CW\*(C`qq/STRING/\*(C'\fR, \f(CW\*(C`reverse\*(C'\fR,
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\&\f(CW\*(C`rindex\*(C'\fR, \f(CW\*(C`sprintf\*(C'\fR, \f(CW\*(C`substr\*(C'\fR, \f(CW\*(C`tr///\*(C'\fR, \f(CW\*(C`uc\*(C'\fR, \f(CW\*(C`ucfirst\*(C'\fR, \f(CW\*(C`y///\*(C'\fR
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.IP "Regular expressions and pattern matching" 4
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.IX Xref "regular expression regex regexp"
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.IX Item "Regular expressions and pattern matching"
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\&\f(CW\*(C`m//\*(C'\fR, \f(CW\*(C`pos\*(C'\fR, \f(CW\*(C`quotemeta\*(C'\fR, \f(CW\*(C`s///\*(C'\fR, \f(CW\*(C`split\*(C'\fR, \f(CW\*(C`study\*(C'\fR, \f(CW\*(C`qr//\*(C'\fR
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.IP "Numeric functions" 4
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.IX Xref "numeric number trigonometric trigonometry"
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.IX Item "Numeric functions"
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\&\f(CW\*(C`abs\*(C'\fR, \f(CW\*(C`atan2\*(C'\fR, \f(CW\*(C`cos\*(C'\fR, \f(CW\*(C`exp\*(C'\fR, \f(CW\*(C`hex\*(C'\fR, \f(CW\*(C`int\*(C'\fR, \f(CW\*(C`log\*(C'\fR, \f(CW\*(C`oct\*(C'\fR, \f(CW\*(C`rand\*(C'\fR,
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\&\f(CW\*(C`sin\*(C'\fR, \f(CW\*(C`sqrt\*(C'\fR, \f(CW\*(C`srand\*(C'\fR
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.ie n .IP "Functions for real @ARRAYs" 4
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.el .IP "Functions for real \f(CW@ARRAYs\fR" 4
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.IX Xref "array"
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.IX Item "Functions for real @ARRAYs"
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\&\f(CW\*(C`pop\*(C'\fR, \f(CW\*(C`push\*(C'\fR, \f(CW\*(C`shift\*(C'\fR, \f(CW\*(C`splice\*(C'\fR, \f(CW\*(C`unshift\*(C'\fR
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.IP "Functions for list data" 4
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.IX Xref "list"
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.IX Item "Functions for list data"
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\&\f(CW\*(C`grep\*(C'\fR, \f(CW\*(C`join\*(C'\fR, \f(CW\*(C`map\*(C'\fR, \f(CW\*(C`qw/STRING/\*(C'\fR, \f(CW\*(C`reverse\*(C'\fR, \f(CW\*(C`sort\*(C'\fR, \f(CW\*(C`unpack\*(C'\fR
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.ie n .IP "Functions for real %HASHes" 4
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.el .IP "Functions for real \f(CW%HASHes\fR" 4
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.IX Xref "hash"
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.IX Item "Functions for real %HASHes"
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\&\f(CW\*(C`delete\*(C'\fR, \f(CW\*(C`each\*(C'\fR, \f(CW\*(C`exists\*(C'\fR, \f(CW\*(C`keys\*(C'\fR, \f(CW\*(C`values\*(C'\fR
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.IP "Input and output functions" 4
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.IX Xref "I O input output dbm"
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.IX Item "Input and output functions"
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\&\f(CW\*(C`binmode\*(C'\fR, \f(CW\*(C`close\*(C'\fR, \f(CW\*(C`closedir\*(C'\fR, \f(CW\*(C`dbmclose\*(C'\fR, \f(CW\*(C`dbmopen\*(C'\fR, \f(CW\*(C`die\*(C'\fR, \f(CW\*(C`eof\*(C'\fR,
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\&\f(CW\*(C`fileno\*(C'\fR, \f(CW\*(C`flock\*(C'\fR, \f(CW\*(C`format\*(C'\fR, \f(CW\*(C`getc\*(C'\fR, \f(CW\*(C`print\*(C'\fR, \f(CW\*(C`printf\*(C'\fR, \f(CW\*(C`read\*(C'\fR,
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\&\f(CW\*(C`readdir\*(C'\fR, \f(CW\*(C`rewinddir\*(C'\fR, \f(CW\*(C`seek\*(C'\fR, \f(CW\*(C`seekdir\*(C'\fR, \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`syscall\*(C'\fR,
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\&\f(CW\*(C`sysread\*(C'\fR, \f(CW\*(C`sysseek\*(C'\fR, \f(CW\*(C`syswrite\*(C'\fR, \f(CW\*(C`tell\*(C'\fR, \f(CW\*(C`telldir\*(C'\fR, \f(CW\*(C`truncate\*(C'\fR,
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\&\f(CW\*(C`warn\*(C'\fR, \f(CW\*(C`write\*(C'\fR
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.IP "Functions for fixed length data or records" 4
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.IX Item "Functions for fixed length data or records"
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\&\f(CW\*(C`pack\*(C'\fR, \f(CW\*(C`read\*(C'\fR, \f(CW\*(C`syscall\*(C'\fR, \f(CW\*(C`sysread\*(C'\fR, \f(CW\*(C`syswrite\*(C'\fR, \f(CW\*(C`unpack\*(C'\fR, \f(CW\*(C`vec\*(C'\fR
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.IP "Functions for filehandles, files, or directories" 4
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.IX Xref "file filehandle directory pipe link symlink"
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.IX Item "Functions for filehandles, files, or directories"
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|
\&\f(CW\*(C`\-\f(CIX\f(CW\*(C'\fR, \f(CW\*(C`chdir\*(C'\fR, \f(CW\*(C`chmod\*(C'\fR, \f(CW\*(C`chown\*(C'\fR, \f(CW\*(C`chroot\*(C'\fR, \f(CW\*(C`fcntl\*(C'\fR, \f(CW\*(C`glob\*(C'\fR,
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\&\f(CW\*(C`ioctl\*(C'\fR, \f(CW\*(C`link\*(C'\fR, \f(CW\*(C`lstat\*(C'\fR, \f(CW\*(C`mkdir\*(C'\fR, \f(CW\*(C`open\*(C'\fR, \f(CW\*(C`opendir\*(C'\fR,
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\&\f(CW\*(C`readlink\*(C'\fR, \f(CW\*(C`rename\*(C'\fR, \f(CW\*(C`rmdir\*(C'\fR, \f(CW\*(C`stat\*(C'\fR, \f(CW\*(C`symlink\*(C'\fR, \f(CW\*(C`sysopen\*(C'\fR,
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\&\f(CW\*(C`umask\*(C'\fR, \f(CW\*(C`unlink\*(C'\fR, \f(CW\*(C`utime\*(C'\fR
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.IP "Keywords related to the control flow of your Perl program" 4
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.IX Xref "control flow"
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.IX Item "Keywords related to the control flow of your Perl program"
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|
\&\f(CW\*(C`caller\*(C'\fR, \f(CW\*(C`continue\*(C'\fR, \f(CW\*(C`die\*(C'\fR, \f(CW\*(C`do\*(C'\fR, \f(CW\*(C`dump\*(C'\fR, \f(CW\*(C`eval\*(C'\fR, \f(CW\*(C`exit\*(C'\fR,
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\&\f(CW\*(C`goto\*(C'\fR, \f(CW\*(C`last\*(C'\fR, \f(CW\*(C`next\*(C'\fR, \f(CW\*(C`redo\*(C'\fR, \f(CW\*(C`return\*(C'\fR, \f(CW\*(C`sub\*(C'\fR, \f(CW\*(C`wantarray\*(C'\fR
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.IP "Keywords related to scoping" 4
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|
.IX Item "Keywords related to scoping"
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|
\&\f(CW\*(C`caller\*(C'\fR, \f(CW\*(C`import\*(C'\fR, \f(CW\*(C`local\*(C'\fR, \f(CW\*(C`my\*(C'\fR, \f(CW\*(C`our\*(C'\fR, \f(CW\*(C`package\*(C'\fR, \f(CW\*(C`use\*(C'\fR
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.IP "Miscellaneous functions" 4
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.IX Item "Miscellaneous functions"
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|
\&\f(CW\*(C`defined\*(C'\fR, \f(CW\*(C`dump\*(C'\fR, \f(CW\*(C`eval\*(C'\fR, \f(CW\*(C`formline\*(C'\fR, \f(CW\*(C`local\*(C'\fR, \f(CW\*(C`my\*(C'\fR, \f(CW\*(C`our\*(C'\fR, \f(CW\*(C`reset\*(C'\fR,
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\&\f(CW\*(C`scalar\*(C'\fR, \f(CW\*(C`undef\*(C'\fR, \f(CW\*(C`wantarray\*(C'\fR
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.IP "Functions for processes and process groups" 4
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.IX Xref "process pid process id"
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.IX Item "Functions for processes and process groups"
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\&\f(CW\*(C`alarm\*(C'\fR, \f(CW\*(C`exec\*(C'\fR, \f(CW\*(C`fork\*(C'\fR, \f(CW\*(C`getpgrp\*(C'\fR, \f(CW\*(C`getppid\*(C'\fR, \f(CW\*(C`getpriority\*(C'\fR, \f(CW\*(C`kill\*(C'\fR,
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\&\f(CW\*(C`pipe\*(C'\fR, \f(CW\*(C`qx/STRING/\*(C'\fR, \f(CW\*(C`setpgrp\*(C'\fR, \f(CW\*(C`setpriority\*(C'\fR, \f(CW\*(C`sleep\*(C'\fR, \f(CW\*(C`system\*(C'\fR,
|
|
\&\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`wait\*(C'\fR, \f(CW\*(C`waitpid\*(C'\fR
|
|
.IP "Keywords related to perl modules" 4
|
|
.IX Xref "module"
|
|
.IX Item "Keywords related to perl modules"
|
|
\&\f(CW\*(C`do\*(C'\fR, \f(CW\*(C`import\*(C'\fR, \f(CW\*(C`no\*(C'\fR, \f(CW\*(C`package\*(C'\fR, \f(CW\*(C`require\*(C'\fR, \f(CW\*(C`use\*(C'\fR
|
|
.IP "Keywords related to classes and object-orientedness" 4
|
|
.IX Xref "object class package"
|
|
.IX Item "Keywords related to classes and object-orientedness"
|
|
\&\f(CW\*(C`bless\*(C'\fR, \f(CW\*(C`dbmclose\*(C'\fR, \f(CW\*(C`dbmopen\*(C'\fR, \f(CW\*(C`package\*(C'\fR, \f(CW\*(C`ref\*(C'\fR, \f(CW\*(C`tie\*(C'\fR, \f(CW\*(C`tied\*(C'\fR,
|
|
\&\f(CW\*(C`untie\*(C'\fR, \f(CW\*(C`use\*(C'\fR
|
|
.IP "Low-level socket functions" 4
|
|
.IX Xref "socket sock"
|
|
.IX Item "Low-level socket functions"
|
|
\&\f(CW\*(C`accept\*(C'\fR, \f(CW\*(C`bind\*(C'\fR, \f(CW\*(C`connect\*(C'\fR, \f(CW\*(C`getpeername\*(C'\fR, \f(CW\*(C`getsockname\*(C'\fR,
|
|
\&\f(CW\*(C`getsockopt\*(C'\fR, \f(CW\*(C`listen\*(C'\fR, \f(CW\*(C`recv\*(C'\fR, \f(CW\*(C`send\*(C'\fR, \f(CW\*(C`setsockopt\*(C'\fR, \f(CW\*(C`shutdown\*(C'\fR,
|
|
\&\f(CW\*(C`socket\*(C'\fR, \f(CW\*(C`socketpair\*(C'\fR
|
|
.IP "System V interprocess communication functions" 4
|
|
.IX Xref "IPC System V semaphore shared memory memory message"
|
|
.IX Item "System V interprocess communication functions"
|
|
\&\f(CW\*(C`msgctl\*(C'\fR, \f(CW\*(C`msgget\*(C'\fR, \f(CW\*(C`msgrcv\*(C'\fR, \f(CW\*(C`msgsnd\*(C'\fR, \f(CW\*(C`semctl\*(C'\fR, \f(CW\*(C`semget\*(C'\fR, \f(CW\*(C`semop\*(C'\fR,
|
|
\&\f(CW\*(C`shmctl\*(C'\fR, \f(CW\*(C`shmget\*(C'\fR, \f(CW\*(C`shmread\*(C'\fR, \f(CW\*(C`shmwrite\*(C'\fR
|
|
.IP "Fetching user and group info" 4
|
|
.IX Xref "user group password uid gid passwd etc passwd"
|
|
.IX Item "Fetching user and group info"
|
|
\&\f(CW\*(C`endgrent\*(C'\fR, \f(CW\*(C`endhostent\*(C'\fR, \f(CW\*(C`endnetent\*(C'\fR, \f(CW\*(C`endpwent\*(C'\fR, \f(CW\*(C`getgrent\*(C'\fR,
|
|
\&\f(CW\*(C`getgrgid\*(C'\fR, \f(CW\*(C`getgrnam\*(C'\fR, \f(CW\*(C`getlogin\*(C'\fR, \f(CW\*(C`getpwent\*(C'\fR, \f(CW\*(C`getpwnam\*(C'\fR,
|
|
\&\f(CW\*(C`getpwuid\*(C'\fR, \f(CW\*(C`setgrent\*(C'\fR, \f(CW\*(C`setpwent\*(C'\fR
|
|
.IP "Fetching network info" 4
|
|
.IX Xref "network protocol host hostname IP address service"
|
|
.IX Item "Fetching network info"
|
|
\&\f(CW\*(C`endprotoent\*(C'\fR, \f(CW\*(C`endservent\*(C'\fR, \f(CW\*(C`gethostbyaddr\*(C'\fR, \f(CW\*(C`gethostbyname\*(C'\fR,
|
|
\&\f(CW\*(C`gethostent\*(C'\fR, \f(CW\*(C`getnetbyaddr\*(C'\fR, \f(CW\*(C`getnetbyname\*(C'\fR, \f(CW\*(C`getnetent\*(C'\fR,
|
|
\&\f(CW\*(C`getprotobyname\*(C'\fR, \f(CW\*(C`getprotobynumber\*(C'\fR, \f(CW\*(C`getprotoent\*(C'\fR,
|
|
\&\f(CW\*(C`getservbyname\*(C'\fR, \f(CW\*(C`getservbyport\*(C'\fR, \f(CW\*(C`getservent\*(C'\fR, \f(CW\*(C`sethostent\*(C'\fR,
|
|
\&\f(CW\*(C`setnetent\*(C'\fR, \f(CW\*(C`setprotoent\*(C'\fR, \f(CW\*(C`setservent\*(C'\fR
|
|
.IP "Time-related functions" 4
|
|
.IX Xref "time date"
|
|
.IX Item "Time-related functions"
|
|
\&\f(CW\*(C`gmtime\*(C'\fR, \f(CW\*(C`localtime\*(C'\fR, \f(CW\*(C`time\*(C'\fR, \f(CW\*(C`times\*(C'\fR
|
|
.IP "Functions new in perl5" 4
|
|
.IX Xref "perl5"
|
|
.IX Item "Functions new in perl5"
|
|
\&\f(CW\*(C`abs\*(C'\fR, \f(CW\*(C`bless\*(C'\fR, \f(CW\*(C`chomp\*(C'\fR, \f(CW\*(C`chr\*(C'\fR, \f(CW\*(C`exists\*(C'\fR, \f(CW\*(C`formline\*(C'\fR, \f(CW\*(C`glob\*(C'\fR,
|
|
\&\f(CW\*(C`import\*(C'\fR, \f(CW\*(C`lc\*(C'\fR, \f(CW\*(C`lcfirst\*(C'\fR, \f(CW\*(C`map\*(C'\fR, \f(CW\*(C`my\*(C'\fR, \f(CW\*(C`no\*(C'\fR, \f(CW\*(C`our\*(C'\fR, \f(CW\*(C`prototype\*(C'\fR,
|
|
\&\f(CW\*(C`qx\*(C'\fR, \f(CW\*(C`qw\*(C'\fR, \f(CW\*(C`readline\*(C'\fR, \f(CW\*(C`readpipe\*(C'\fR, \f(CW\*(C`ref\*(C'\fR, \f(CW\*(C`sub*\*(C'\fR, \f(CW\*(C`sysopen\*(C'\fR, \f(CW\*(C`tie\*(C'\fR,
|
|
\&\f(CW\*(C`tied\*(C'\fR, \f(CW\*(C`uc\*(C'\fR, \f(CW\*(C`ucfirst\*(C'\fR, \f(CW\*(C`untie\*(C'\fR, \f(CW\*(C`use\*(C'\fR
|
|
.Sp
|
|
* \- \f(CW\*(C`sub\*(C'\fR was a keyword in perl4, but in perl5 it is an
|
|
operator, which can be used in expressions.
|
|
.IP "Functions obsoleted in perl5" 4
|
|
.IX Item "Functions obsoleted in perl5"
|
|
\&\f(CW\*(C`dbmclose\*(C'\fR, \f(CW\*(C`dbmopen\*(C'\fR
|
|
.Sh "Portability"
|
|
.IX Xref "portability Unix portable"
|
|
.IX Subsection "Portability"
|
|
Perl was born in Unix and can therefore access all common Unix
|
|
system calls. In non-Unix environments, the functionality of some
|
|
Unix system calls may not be available, or details of the available
|
|
functionality may differ slightly. The Perl functions affected
|
|
by this are:
|
|
.PP
|
|
\&\f(CW\*(C`\-X\*(C'\fR, \f(CW\*(C`binmode\*(C'\fR, \f(CW\*(C`chmod\*(C'\fR, \f(CW\*(C`chown\*(C'\fR, \f(CW\*(C`chroot\*(C'\fR, \f(CW\*(C`crypt\*(C'\fR,
|
|
\&\f(CW\*(C`dbmclose\*(C'\fR, \f(CW\*(C`dbmopen\*(C'\fR, \f(CW\*(C`dump\*(C'\fR, \f(CW\*(C`endgrent\*(C'\fR, \f(CW\*(C`endhostent\*(C'\fR,
|
|
\&\f(CW\*(C`endnetent\*(C'\fR, \f(CW\*(C`endprotoent\*(C'\fR, \f(CW\*(C`endpwent\*(C'\fR, \f(CW\*(C`endservent\*(C'\fR, \f(CW\*(C`exec\*(C'\fR,
|
|
\&\f(CW\*(C`fcntl\*(C'\fR, \f(CW\*(C`flock\*(C'\fR, \f(CW\*(C`fork\*(C'\fR, \f(CW\*(C`getgrent\*(C'\fR, \f(CW\*(C`getgrgid\*(C'\fR, \f(CW\*(C`gethostbyname\*(C'\fR,
|
|
\&\f(CW\*(C`gethostent\*(C'\fR, \f(CW\*(C`getlogin\*(C'\fR, \f(CW\*(C`getnetbyaddr\*(C'\fR, \f(CW\*(C`getnetbyname\*(C'\fR, \f(CW\*(C`getnetent\*(C'\fR,
|
|
\&\f(CW\*(C`getppid\*(C'\fR, \f(CW\*(C`getpgrp\*(C'\fR, \f(CW\*(C`getpriority\*(C'\fR, \f(CW\*(C`getprotobynumber\*(C'\fR,
|
|
\&\f(CW\*(C`getprotoent\*(C'\fR, \f(CW\*(C`getpwent\*(C'\fR, \f(CW\*(C`getpwnam\*(C'\fR, \f(CW\*(C`getpwuid\*(C'\fR,
|
|
\&\f(CW\*(C`getservbyport\*(C'\fR, \f(CW\*(C`getservent\*(C'\fR, \f(CW\*(C`getsockopt\*(C'\fR, \f(CW\*(C`glob\*(C'\fR, \f(CW\*(C`ioctl\*(C'\fR,
|
|
\&\f(CW\*(C`kill\*(C'\fR, \f(CW\*(C`link\*(C'\fR, \f(CW\*(C`lstat\*(C'\fR, \f(CW\*(C`msgctl\*(C'\fR, \f(CW\*(C`msgget\*(C'\fR, \f(CW\*(C`msgrcv\*(C'\fR,
|
|
\&\f(CW\*(C`msgsnd\*(C'\fR, \f(CW\*(C`open\*(C'\fR, \f(CW\*(C`pipe\*(C'\fR, \f(CW\*(C`readlink\*(C'\fR, \f(CW\*(C`rename\*(C'\fR, \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`semctl\*(C'\fR,
|
|
\&\f(CW\*(C`semget\*(C'\fR, \f(CW\*(C`semop\*(C'\fR, \f(CW\*(C`setgrent\*(C'\fR, \f(CW\*(C`sethostent\*(C'\fR, \f(CW\*(C`setnetent\*(C'\fR,
|
|
\&\f(CW\*(C`setpgrp\*(C'\fR, \f(CW\*(C`setpriority\*(C'\fR, \f(CW\*(C`setprotoent\*(C'\fR, \f(CW\*(C`setpwent\*(C'\fR,
|
|
\&\f(CW\*(C`setservent\*(C'\fR, \f(CW\*(C`setsockopt\*(C'\fR, \f(CW\*(C`shmctl\*(C'\fR, \f(CW\*(C`shmget\*(C'\fR, \f(CW\*(C`shmread\*(C'\fR,
|
|
\&\f(CW\*(C`shmwrite\*(C'\fR, \f(CW\*(C`socket\*(C'\fR, \f(CW\*(C`socketpair\*(C'\fR,
|
|
\&\f(CW\*(C`stat\*(C'\fR, \f(CW\*(C`symlink\*(C'\fR, \f(CW\*(C`syscall\*(C'\fR, \f(CW\*(C`sysopen\*(C'\fR, \f(CW\*(C`system\*(C'\fR,
|
|
\&\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`truncate\*(C'\fR, \f(CW\*(C`umask\*(C'\fR, \f(CW\*(C`unlink\*(C'\fR,
|
|
\&\f(CW\*(C`utime\*(C'\fR, \f(CW\*(C`wait\*(C'\fR, \f(CW\*(C`waitpid\*(C'\fR
|
|
.PP
|
|
For more information about the portability of these functions, see
|
|
perlport and other available platform-specific documentation.
|
|
.Sh "Alphabetical Listing of Perl Functions"
|
|
.IX Subsection "Alphabetical Listing of Perl Functions"
|
|
.IP "\-X \s-1FILEHANDLE\s0" 8
|
|
.IX Xref "-r -w -x -o -R -W -X -O -e -z -s -f -d -l -p -S -b -c -t -u -g -k -T -B -M -A -C"
|
|
.IX Item "-X FILEHANDLE"
|
|
.PD 0
|
|
.IP "\-X \s-1EXPR\s0" 8
|
|
.IX Item "-X EXPR"
|
|
.IP "\-X" 8
|
|
.IX Item "-X"
|
|
.PD
|
|
A file test, where X is one of the letters listed below. This unary
|
|
operator takes one argument, either a filename or a filehandle, and
|
|
tests the associated file to see if something is true about it. If the
|
|
argument is omitted, tests \f(CW$_\fR, except for \f(CW\*(C`\-t\*(C'\fR, which tests \s-1STDIN\s0.
|
|
Unless otherwise documented, it returns \f(CW1\fR for true and \f(CW''\fR for false, or
|
|
the undefined value if the file doesn't exist. Despite the funny
|
|
names, precedence is the same as any other named unary operator, and
|
|
the argument may be parenthesized like any other unary operator. The
|
|
operator may be any of:
|
|
.Sp
|
|
.Vb 4
|
|
\& -r File is readable by effective uid/gid.
|
|
\& -w File is writable by effective uid/gid.
|
|
\& -x File is executable by effective uid/gid.
|
|
\& -o File is owned by effective uid.
|
|
.Ve
|
|
.Sp
|
|
.Vb 4
|
|
\& -R File is readable by real uid/gid.
|
|
\& -W File is writable by real uid/gid.
|
|
\& -X File is executable by real uid/gid.
|
|
\& -O File is owned by real uid.
|
|
.Ve
|
|
.Sp
|
|
.Vb 3
|
|
\& -e File exists.
|
|
\& -z File has zero size (is empty).
|
|
\& -s File has nonzero size (returns size in bytes).
|
|
.Ve
|
|
.Sp
|
|
.Vb 8
|
|
\& -f File is a plain file.
|
|
\& -d File is a directory.
|
|
\& -l File is a symbolic link.
|
|
\& -p File is a named pipe (FIFO), or Filehandle is a pipe.
|
|
\& -S File is a socket.
|
|
\& -b File is a block special file.
|
|
\& -c File is a character special file.
|
|
\& -t Filehandle is opened to a tty.
|
|
.Ve
|
|
.Sp
|
|
.Vb 3
|
|
\& -u File has setuid bit set.
|
|
\& -g File has setgid bit set.
|
|
\& -k File has sticky bit set.
|
|
.Ve
|
|
.Sp
|
|
.Vb 2
|
|
\& -T File is an ASCII text file (heuristic guess).
|
|
\& -B File is a "binary" file (opposite of -T).
|
|
.Ve
|
|
.Sp
|
|
.Vb 3
|
|
\& -M Script start time minus file modification time, in days.
|
|
\& -A Same for access time.
|
|
\& -C Same for inode change time (Unix, may differ for other platforms)
|
|
.Ve
|
|
.Sp
|
|
Example:
|
|
.Sp
|
|
.Vb 5
|
|
\& while (<>) {
|
|
\& chomp;
|
|
\& next unless -f $_; # ignore specials
|
|
\& #...
|
|
\& }
|
|
.Ve
|
|
.Sp
|
|
The interpretation of the file permission operators \f(CW\*(C`\-r\*(C'\fR, \f(CW\*(C`\-R\*(C'\fR,
|
|
\&\f(CW\*(C`\-w\*(C'\fR, \f(CW\*(C`\-W\*(C'\fR, \f(CW\*(C`\-x\*(C'\fR, and \f(CW\*(C`\-X\*(C'\fR is by default based solely on the mode
|
|
of the file and the uids and gids of the user. There may be other
|
|
reasons you can't actually read, write, or execute the file. Such
|
|
reasons may be for example network filesystem access controls, ACLs
|
|
(access control lists), read-only filesystems, and unrecognized
|
|
executable formats.
|
|
.Sp
|
|
Also note that, for the superuser on the local filesystems, the \f(CW\*(C`\-r\*(C'\fR,
|
|
\&\f(CW\*(C`\-R\*(C'\fR, \f(CW\*(C`\-w\*(C'\fR, and \f(CW\*(C`\-W\*(C'\fR tests always return 1, and \f(CW\*(C`\-x\*(C'\fR and \f(CW\*(C`\-X\*(C'\fR return 1
|
|
if any execute bit is set in the mode. Scripts run by the superuser
|
|
may thus need to do a \fIstat()\fR to determine the actual mode of the file,
|
|
or temporarily set their effective uid to something else.
|
|
.Sp
|
|
If you are using ACLs, there is a pragma called \f(CW\*(C`filetest\*(C'\fR that may
|
|
produce more accurate results than the bare \fIstat()\fR mode bits.
|
|
When under the \f(CW\*(C`use filetest 'access'\*(C'\fR the above-mentioned filetests
|
|
will test whether the permission can (not) be granted using the
|
|
\&\fIaccess()\fR family of system calls. Also note that the \f(CW\*(C`\-x\*(C'\fR and \f(CW\*(C`\-X\*(C'\fR may
|
|
under this pragma return true even if there are no execute permission
|
|
bits set (nor any extra execute permission ACLs). This strangeness is
|
|
due to the underlying system calls' definitions. Read the
|
|
documentation for the \f(CW\*(C`filetest\*(C'\fR pragma for more information.
|
|
.Sp
|
|
Note that \f(CW\*(C`\-s/a/b/\*(C'\fR does not do a negated substitution. Saying
|
|
\&\f(CW\*(C`\-exp($foo)\*(C'\fR still works as expected, however\*(--only single letters
|
|
following a minus are interpreted as file tests.
|
|
.Sp
|
|
The \f(CW\*(C`\-T\*(C'\fR and \f(CW\*(C`\-B\*(C'\fR switches work as follows. The first block or so of the
|
|
file is examined for odd characters such as strange control codes or
|
|
characters with the high bit set. If too many strange characters (>30%)
|
|
are found, it's a \f(CW\*(C`\-B\*(C'\fR file; otherwise it's a \f(CW\*(C`\-T\*(C'\fR file. Also, any file
|
|
containing null in the first block is considered a binary file. If \f(CW\*(C`\-T\*(C'\fR
|
|
or \f(CW\*(C`\-B\*(C'\fR is used on a filehandle, the current \s-1IO\s0 buffer is examined
|
|
rather than the first block. Both \f(CW\*(C`\-T\*(C'\fR and \f(CW\*(C`\-B\*(C'\fR return true on a null
|
|
file, or a file at \s-1EOF\s0 when testing a filehandle. Because you have to
|
|
read a file to do the \f(CW\*(C`\-T\*(C'\fR test, on most occasions you want to use a \f(CW\*(C`\-f\*(C'\fR
|
|
against the file first, as in \f(CW\*(C`next unless \-f $file && \-T $file\*(C'\fR.
|
|
.Sp
|
|
If any of the file tests (or either the \f(CW\*(C`stat\*(C'\fR or \f(CW\*(C`lstat\*(C'\fR operators) are given
|
|
the special filehandle consisting of a solitary underline, then the stat
|
|
structure of the previous file test (or stat operator) is used, saving
|
|
a system call. (This doesn't work with \f(CW\*(C`\-t\*(C'\fR, and you need to remember
|
|
that \fIlstat()\fR and \f(CW\*(C`\-l\*(C'\fR will leave values in the stat structure for the
|
|
symbolic link, not the real file.) (Also, if the stat buffer was filled by
|
|
an \f(CW\*(C`lstat\*(C'\fR call, \f(CW\*(C`\-T\*(C'\fR and \f(CW\*(C`\-B\*(C'\fR will reset it with the results of \f(CW\*(C`stat _\*(C'\fR).
|
|
Example:
|
|
.Sp
|
|
.Vb 1
|
|
\& print "Can do.\en" if -r $a || -w _ || -x _;
|
|
.Ve
|
|
.Sp
|
|
.Vb 9
|
|
\& stat($filename);
|
|
\& print "Readable\en" if -r _;
|
|
\& print "Writable\en" if -w _;
|
|
\& print "Executable\en" if -x _;
|
|
\& print "Setuid\en" if -u _;
|
|
\& print "Setgid\en" if -g _;
|
|
\& print "Sticky\en" if -k _;
|
|
\& print "Text\en" if -T _;
|
|
\& print "Binary\en" if -B _;
|
|
.Ve
|
|
.IP "abs \s-1VALUE\s0" 8
|
|
.IX Xref "abs absolute"
|
|
.IX Item "abs VALUE"
|
|
.PD 0
|
|
.IP "abs" 8
|
|
.IX Item "abs"
|
|
.PD
|
|
Returns the absolute value of its argument.
|
|
If \s-1VALUE\s0 is omitted, uses \f(CW$_\fR.
|
|
.IP "accept \s-1NEWSOCKET\s0,GENERICSOCKET" 8
|
|
.IX Xref "accept"
|
|
.IX Item "accept NEWSOCKET,GENERICSOCKET"
|
|
Accepts an incoming socket connect, just as the \fIaccept\fR\|(2) system call
|
|
does. Returns the packed address if it succeeded, false otherwise.
|
|
See the example in \*(L"Sockets: Client/Server Communication\*(R" in perlipc.
|
|
.Sp
|
|
On systems that support a close-on-exec flag on files, the flag will
|
|
be set for the newly opened file descriptor, as determined by the
|
|
value of $^F. See \*(L"$^F\*(R" in perlvar.
|
|
.IP "alarm \s-1SECONDS\s0" 8
|
|
.IX Xref "alarm SIGALRM timer"
|
|
.IX Item "alarm SECONDS"
|
|
.PD 0
|
|
.IP "alarm" 8
|
|
.IX Item "alarm"
|
|
.PD
|
|
Arranges to have a \s-1SIGALRM\s0 delivered to this process after the
|
|
specified number of wallclock seconds has elapsed. If \s-1SECONDS\s0 is not
|
|
specified, the value stored in \f(CW$_\fR is used. (On some machines,
|
|
unfortunately, the elapsed time may be up to one second less or more
|
|
than you specified because of how seconds are counted, and process
|
|
scheduling may delay the delivery of the signal even further.)
|
|
.Sp
|
|
Only one timer may be counting at once. Each call disables the
|
|
previous timer, and an argument of \f(CW0\fR may be supplied to cancel the
|
|
previous timer without starting a new one. The returned value is the
|
|
amount of time remaining on the previous timer.
|
|
.Sp
|
|
For delays of finer granularity than one second, you may use Perl's
|
|
four-argument version of \fIselect()\fR leaving the first three arguments
|
|
undefined, or you might be able to use the \f(CW\*(C`syscall\*(C'\fR interface to
|
|
access \fIsetitimer\fR\|(2) if your system supports it. The Time::HiRes
|
|
module (from \s-1CPAN\s0, and starting from Perl 5.8 part of the standard
|
|
distribution) may also prove useful.
|
|
.Sp
|
|
It is usually a mistake to intermix \f(CW\*(C`alarm\*(C'\fR and \f(CW\*(C`sleep\*(C'\fR calls.
|
|
(\f(CW\*(C`sleep\*(C'\fR may be internally implemented in your system with \f(CW\*(C`alarm\*(C'\fR)
|
|
.Sp
|
|
If you want to use \f(CW\*(C`alarm\*(C'\fR to time out a system call you need to use an
|
|
\&\f(CW\*(C`eval\*(C'\fR/\f(CW\*(C`die\*(C'\fR pair. You can't rely on the alarm causing the system call to
|
|
fail with \f(CW$!\fR set to \f(CW\*(C`EINTR\*(C'\fR because Perl sets up signal handlers to
|
|
restart system calls on some systems. Using \f(CW\*(C`eval\*(C'\fR/\f(CW\*(C`die\*(C'\fR always works,
|
|
modulo the caveats given in \*(L"Signals\*(R" in perlipc.
|
|
.Sp
|
|
.Vb 13
|
|
\& eval {
|
|
\& local $SIG{ALRM} = sub { die "alarm\en" }; # NB: \en required
|
|
\& alarm $timeout;
|
|
\& $nread = sysread SOCKET, $buffer, $size;
|
|
\& alarm 0;
|
|
\& };
|
|
\& if ($@) {
|
|
\& die unless $@ eq "alarm\en"; # propagate unexpected errors
|
|
\& # timed out
|
|
\& }
|
|
\& else {
|
|
\& # didn't
|
|
\& }
|
|
.Ve
|
|
.Sp
|
|
For more information see perlipc.
|
|
.IP "atan2 Y,X" 8
|
|
.IX Xref "atan2 arctangent tan tangent"
|
|
.IX Item "atan2 Y,X"
|
|
Returns the arctangent of Y/X in the range \-PI to \s-1PI\s0.
|
|
.Sp
|
|
For the tangent operation, you may use the \f(CW\*(C`Math::Trig::tan\*(C'\fR
|
|
function, or use the familiar relation:
|
|
.Sp
|
|
.Vb 1
|
|
\& sub tan { sin($_[0]) / cos($_[0]) }
|
|
.Ve
|
|
.Sp
|
|
Note that atan2(0, 0) is not well\-defined.
|
|
.IP "bind \s-1SOCKET\s0,NAME" 8
|
|
.IX Xref "bind"
|
|
.IX Item "bind SOCKET,NAME"
|
|
Binds a network address to a socket, just as the bind system call
|
|
does. Returns true if it succeeded, false otherwise. \s-1NAME\s0 should be a
|
|
packed address of the appropriate type for the socket. See the examples in
|
|
\&\*(L"Sockets: Client/Server Communication\*(R" in perlipc.
|
|
.IP "binmode \s-1FILEHANDLE\s0, \s-1LAYER\s0" 8
|
|
.IX Xref "binmode binary text DOS Windows"
|
|
.IX Item "binmode FILEHANDLE, LAYER"
|
|
.PD 0
|
|
.IP "binmode \s-1FILEHANDLE\s0" 8
|
|
.IX Item "binmode FILEHANDLE"
|
|
.PD
|
|
Arranges for \s-1FILEHANDLE\s0 to be read or written in \*(L"binary\*(R" or \*(L"text\*(R"
|
|
mode on systems where the run-time libraries distinguish between
|
|
binary and text files. If \s-1FILEHANDLE\s0 is an expression, the value is
|
|
taken as the name of the filehandle. Returns true on success,
|
|
otherwise it returns \f(CW\*(C`undef\*(C'\fR and sets \f(CW$!\fR (errno).
|
|
.Sp
|
|
On some systems (in general, \s-1DOS\s0 and Windows-based systems) \fIbinmode()\fR
|
|
is necessary when you're not working with a text file. For the sake
|
|
of portability it is a good idea to always use it when appropriate,
|
|
and to never use it when it isn't appropriate. Also, people can
|
|
set their I/O to be by default \s-1UTF\-8\s0 encoded Unicode, not bytes.
|
|
.Sp
|
|
In other words: regardless of platform, use \fIbinmode()\fR on binary data,
|
|
like for example images.
|
|
.Sp
|
|
If \s-1LAYER\s0 is present it is a single string, but may contain multiple
|
|
directives. The directives alter the behaviour of the file handle.
|
|
When \s-1LAYER\s0 is present using binmode on text file makes sense.
|
|
.Sp
|
|
If \s-1LAYER\s0 is omitted or specified as \f(CW\*(C`:raw\*(C'\fR the filehandle is made
|
|
suitable for passing binary data. This includes turning off possible \s-1CRLF\s0
|
|
translation and marking it as bytes (as opposed to Unicode characters).
|
|
Note that, despite what may be implied in \fI\*(L"Programming Perl\*(R"\fR (the
|
|
Camel) or elsewhere, \f(CW\*(C`:raw\*(C'\fR is \fInot\fR the simply inverse of \f(CW\*(C`:crlf\*(C'\fR
|
|
\&\*(-- other layers which would affect binary nature of the stream are
|
|
\&\fIalso\fR disabled. See PerlIO, perlrun and the discussion about the
|
|
\&\s-1PERLIO\s0 environment variable.
|
|
.Sp
|
|
The \f(CW\*(C`:bytes\*(C'\fR, \f(CW\*(C`:crlf\*(C'\fR, and \f(CW\*(C`:utf8\*(C'\fR, and any other directives of the
|
|
form \f(CW\*(C`:...\*(C'\fR, are called I/O \fIlayers\fR. The \f(CW\*(C`open\*(C'\fR pragma can be used to
|
|
establish default I/O layers. See open.
|
|
.Sp
|
|
\&\fIThe \s-1LAYER\s0 parameter of the \fIbinmode()\fI function is described as \*(L"\s-1DISCIPLINE\s0\*(R"
|
|
in \*(L"Programming Perl, 3rd Edition\*(R". However, since the publishing of this
|
|
book, by many known as \*(L"Camel \s-1III\s0\*(R", the consensus of the naming of this
|
|
functionality has moved from \*(L"discipline\*(R" to \*(L"layer\*(R". All documentation
|
|
of this version of Perl therefore refers to \*(L"layers\*(R" rather than to
|
|
\&\*(L"disciplines\*(R". Now back to the regularly scheduled documentation...\fR
|
|
.Sp
|
|
To mark \s-1FILEHANDLE\s0 as \s-1UTF\-8\s0, use \f(CW\*(C`:utf8\*(C'\fR.
|
|
.Sp
|
|
In general, \fIbinmode()\fR should be called after \fIopen()\fR but before any I/O
|
|
is done on the filehandle. Calling \fIbinmode()\fR will normally flush any
|
|
pending buffered output data (and perhaps pending input data) on the
|
|
handle. An exception to this is the \f(CW\*(C`:encoding\*(C'\fR layer that
|
|
changes the default character encoding of the handle, see open.
|
|
The \f(CW\*(C`:encoding\*(C'\fR layer sometimes needs to be called in
|
|
mid\-stream, and it doesn't flush the stream. The \f(CW\*(C`:encoding\*(C'\fR
|
|
also implicitly pushes on top of itself the \f(CW\*(C`:utf8\*(C'\fR layer because
|
|
internally Perl will operate on \s-1UTF\-8\s0 encoded Unicode characters.
|
|
.Sp
|
|
The operating system, device drivers, C libraries, and Perl run-time
|
|
system all work together to let the programmer treat a single
|
|
character (\f(CW\*(C`\en\*(C'\fR) as the line terminator, irrespective of the external
|
|
representation. On many operating systems, the native text file
|
|
representation matches the internal representation, but on some
|
|
platforms the external representation of \f(CW\*(C`\en\*(C'\fR is made up of more than
|
|
one character.
|
|
.Sp
|
|
Mac \s-1OS\s0, all variants of Unix, and Stream_LF files on \s-1VMS\s0 use a single
|
|
character to end each line in the external representation of text (even
|
|
though that single character is \s-1CARRIAGE\s0 \s-1RETURN\s0 on Mac \s-1OS\s0 and \s-1LINE\s0 \s-1FEED\s0
|
|
on Unix and most \s-1VMS\s0 files). In other systems like \s-1OS/2\s0, \s-1DOS\s0 and the
|
|
various flavors of MS-Windows your program sees a \f(CW\*(C`\en\*(C'\fR as a simple \f(CW\*(C`\ecJ\*(C'\fR,
|
|
but what's stored in text files are the two characters \f(CW\*(C`\ecM\ecJ\*(C'\fR. That
|
|
means that, if you don't use \fIbinmode()\fR on these systems, \f(CW\*(C`\ecM\ecJ\*(C'\fR
|
|
sequences on disk will be converted to \f(CW\*(C`\en\*(C'\fR on input, and any \f(CW\*(C`\en\*(C'\fR in
|
|
your program will be converted back to \f(CW\*(C`\ecM\ecJ\*(C'\fR on output. This is what
|
|
you want for text files, but it can be disastrous for binary files.
|
|
.Sp
|
|
Another consequence of using \fIbinmode()\fR (on some systems) is that
|
|
special end-of-file markers will be seen as part of the data stream.
|
|
For systems from the Microsoft family this means that if your binary
|
|
data contains \f(CW\*(C`\ecZ\*(C'\fR, the I/O subsystem will regard it as the end of
|
|
the file, unless you use \fIbinmode()\fR.
|
|
.Sp
|
|
\&\fIbinmode()\fR is not only important for \fIreadline()\fR and \fIprint()\fR operations,
|
|
but also when using \fIread()\fR, \fIseek()\fR, \fIsysread()\fR, \fIsyswrite()\fR and \fItell()\fR
|
|
(see perlport for more details). See the \f(CW$/\fR and \f(CW\*(C`$\e\*(C'\fR variables
|
|
in perlvar for how to manually set your input and output
|
|
line-termination sequences.
|
|
.IP "bless \s-1REF\s0,CLASSNAME" 8
|
|
.IX Xref "bless"
|
|
.IX Item "bless REF,CLASSNAME"
|
|
.PD 0
|
|
.IP "bless \s-1REF\s0" 8
|
|
.IX Item "bless REF"
|
|
.PD
|
|
This function tells the thingy referenced by \s-1REF\s0 that it is now an object
|
|
in the \s-1CLASSNAME\s0 package. If \s-1CLASSNAME\s0 is omitted, the current package
|
|
is used. Because a \f(CW\*(C`bless\*(C'\fR is often the last thing in a constructor,
|
|
it returns the reference for convenience. Always use the two-argument
|
|
version if a derived class might inherit the function doing the blessing.
|
|
See perltoot and perlobj for more about the blessing (and blessings)
|
|
of objects.
|
|
.Sp
|
|
Consider always blessing objects in CLASSNAMEs that are mixed case.
|
|
Namespaces with all lowercase names are considered reserved for
|
|
Perl pragmata. Builtin types have all uppercase names. To prevent
|
|
confusion, you may wish to avoid such package names as well. Make sure
|
|
that \s-1CLASSNAME\s0 is a true value.
|
|
.Sp
|
|
See \*(L"Perl Modules\*(R" in perlmod.
|
|
.IP "caller \s-1EXPR\s0" 8
|
|
.IX Xref "caller call stack stack stack trace"
|
|
.IX Item "caller EXPR"
|
|
.PD 0
|
|
.IP "caller" 8
|
|
.IX Item "caller"
|
|
.PD
|
|
Returns the context of the current subroutine call. In scalar context,
|
|
returns the caller's package name if there is a caller, that is, if
|
|
we're in a subroutine or \f(CW\*(C`eval\*(C'\fR or \f(CW\*(C`require\*(C'\fR, and the undefined value
|
|
otherwise. In list context, returns
|
|
.Sp
|
|
.Vb 1
|
|
\& ($package, $filename, $line) = caller;
|
|
.Ve
|
|
.Sp
|
|
With \s-1EXPR\s0, it returns some extra information that the debugger uses to
|
|
print a stack trace. The value of \s-1EXPR\s0 indicates how many call frames
|
|
to go back before the current one.
|
|
.Sp
|
|
.Vb 2
|
|
\& ($package, $filename, $line, $subroutine, $hasargs,
|
|
\& $wantarray, $evaltext, $is_require, $hints, $bitmask) = caller($i);
|
|
.Ve
|
|
.Sp
|
|
Here \f(CW$subroutine\fR may be \f(CW\*(C`(eval)\*(C'\fR if the frame is not a subroutine
|
|
call, but an \f(CW\*(C`eval\*(C'\fR. In such a case additional elements \f(CW$evaltext\fR and
|
|
\&\f(CW$is_require\fR are set: \f(CW$is_require\fR is true if the frame is created by a
|
|
\&\f(CW\*(C`require\*(C'\fR or \f(CW\*(C`use\*(C'\fR statement, \f(CW$evaltext\fR contains the text of the
|
|
\&\f(CW\*(C`eval EXPR\*(C'\fR statement. In particular, for an \f(CW\*(C`eval BLOCK\*(C'\fR statement,
|
|
\&\f(CW$filename\fR is \f(CW\*(C`(eval)\*(C'\fR, but \f(CW$evaltext\fR is undefined. (Note also that
|
|
each \f(CW\*(C`use\*(C'\fR statement creates a \f(CW\*(C`require\*(C'\fR frame inside an \f(CW\*(C`eval EXPR\*(C'\fR
|
|
frame.) \f(CW$subroutine\fR may also be \f(CW\*(C`(unknown)\*(C'\fR if this particular
|
|
subroutine happens to have been deleted from the symbol table.
|
|
\&\f(CW$hasargs\fR is true if a new instance of \f(CW@_\fR was set up for the frame.
|
|
\&\f(CW$hints\fR and \f(CW$bitmask\fR contain pragmatic hints that the caller was
|
|
compiled with. The \f(CW$hints\fR and \f(CW$bitmask\fR values are subject to change
|
|
between versions of Perl, and are not meant for external use.
|
|
.Sp
|
|
Furthermore, when called from within the \s-1DB\s0 package, caller returns more
|
|
detailed information: it sets the list variable \f(CW@DB::args\fR to be the
|
|
arguments with which the subroutine was invoked.
|
|
.Sp
|
|
Be aware that the optimizer might have optimized call frames away before
|
|
\&\f(CW\*(C`caller\*(C'\fR had a chance to get the information. That means that \f(CWcaller(N)\fR
|
|
might not return information about the call frame you expect it do, for
|
|
\&\f(CW\*(C`N > 1\*(C'\fR. In particular, \f(CW@DB::args\fR might have information from the
|
|
previous time \f(CW\*(C`caller\*(C'\fR was called.
|
|
.IP "chdir \s-1EXPR\s0" 8
|
|
.IX Xref "chdir cd"
|
|
.IX Item "chdir EXPR"
|
|
.PD 0
|
|
.IP "chdir \s-1FILEHANDLE\s0" 8
|
|
.IX Item "chdir FILEHANDLE"
|
|
.IP "chdir \s-1DIRHANDLE\s0" 8
|
|
.IX Item "chdir DIRHANDLE"
|
|
.IP "chdir" 8
|
|
.IX Item "chdir"
|
|
.PD
|
|
Changes the working directory to \s-1EXPR\s0, if possible. If \s-1EXPR\s0 is omitted,
|
|
changes to the directory specified by \f(CW$ENV{HOME}\fR, if set; if not,
|
|
changes to the directory specified by \f(CW$ENV{LOGDIR}\fR. (Under \s-1VMS\s0, the
|
|
variable \f(CW$ENV{SYS$LOGIN}\fR is also checked, and used if it is set.) If
|
|
neither is set, \f(CW\*(C`chdir\*(C'\fR does nothing. It returns true upon success,
|
|
false otherwise. See the example under \f(CW\*(C`die\*(C'\fR.
|
|
.Sp
|
|
On systems that support fchdir, you might pass a file handle or
|
|
directory handle as argument. On systems that don't support fchdir,
|
|
passing handles produces a fatal error at run time.
|
|
.IP "chmod \s-1LIST\s0" 8
|
|
.IX Xref "chmod permission mode"
|
|
.IX Item "chmod LIST"
|
|
Changes the permissions of a list of files. The first element of the
|
|
list must be the numerical mode, which should probably be an octal
|
|
number, and which definitely should \fInot\fR be a string of octal digits:
|
|
\&\f(CW0644\fR is okay, \f(CW'0644'\fR is not. Returns the number of files
|
|
successfully changed. See also \*(L"oct\*(R", if all you have is a string.
|
|
.Sp
|
|
.Vb 6
|
|
\& $cnt = chmod 0755, 'foo', 'bar';
|
|
\& chmod 0755, @executables;
|
|
\& $mode = '0644'; chmod $mode, 'foo'; # !!! sets mode to
|
|
\& # --w----r-T
|
|
\& $mode = '0644'; chmod oct($mode), 'foo'; # this is better
|
|
\& $mode = 0644; chmod $mode, 'foo'; # this is best
|
|
.Ve
|
|
.Sp
|
|
On systems that support fchmod, you might pass file handles among the
|
|
files. On systems that don't support fchmod, passing file handles
|
|
produces a fatal error at run time.
|
|
.Sp
|
|
.Vb 3
|
|
\& open(my $fh, "<", "foo");
|
|
\& my $perm = (stat $fh)[2] & 07777;
|
|
\& chmod($perm | 0600, $fh);
|
|
.Ve
|
|
.Sp
|
|
You can also import the symbolic \f(CW\*(C`S_I*\*(C'\fR constants from the Fcntl
|
|
module:
|
|
.Sp
|
|
.Vb 1
|
|
\& use Fcntl ':mode';
|
|
.Ve
|
|
.Sp
|
|
.Vb 2
|
|
\& chmod S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH, @executables;
|
|
\& # This is identical to the chmod 0755 of the above example.
|
|
.Ve
|
|
.IP "chomp \s-1VARIABLE\s0" 8
|
|
.IX Xref "chomp INPUT_RECORD_SEPARATOR $ newline eol"
|
|
.IX Item "chomp VARIABLE"
|
|
.PD 0
|
|
.IP "chomp( \s-1LIST\s0 )" 8
|
|
.IX Item "chomp( LIST )"
|
|
.IP "chomp" 8
|
|
.IX Item "chomp"
|
|
.PD
|
|
This safer version of \*(L"chop\*(R" removes any trailing string
|
|
that corresponds to the current value of \f(CW$/\fR (also known as
|
|
\&\f(CW$INPUT_RECORD_SEPARATOR\fR in the \f(CW\*(C`English\*(C'\fR module). It returns the total
|
|
number of characters removed from all its arguments. It's often used to
|
|
remove the newline from the end of an input record when you're worried
|
|
that the final record may be missing its newline. When in paragraph
|
|
mode (\f(CW\*(C`$/ = ""\*(C'\fR), it removes all trailing newlines from the string.
|
|
When in slurp mode (\f(CW\*(C`$/ = undef\*(C'\fR) or fixed-length record mode (\f(CW$/\fR is
|
|
a reference to an integer or the like, see perlvar) \fIchomp()\fR won't
|
|
remove anything.
|
|
If \s-1VARIABLE\s0 is omitted, it chomps \f(CW$_\fR. Example:
|
|
.Sp
|
|
.Vb 5
|
|
\& while (<>) {
|
|
\& chomp; # avoid \en on last field
|
|
\& @array = split(/:/);
|
|
\& # ...
|
|
\& }
|
|
.Ve
|
|
.Sp
|
|
If \s-1VARIABLE\s0 is a hash, it chomps the hash's values, but not its keys.
|
|
.Sp
|
|
|