Built-in Function Overview

People's Choice Award Winning Functions

File and Directory Operations

chmod (list)

just like in UNIX

chown (list)

just like in UNIX

mkdir (dir, mode)

just like in UNIX

print [filehandle] [list]

print stuff to a filehandle, if filehandle is omitted, STDOUT is assumes

printf [filehandle] [list]

like print(), but can do formatted prints using C-like printf() codes

rename (old_name, new_name)

rename a file

rmdir (dir)

remove and empty directory

seek (filehandle, position, whence)

go a file pointer to a particular location within an open file

stat (filename)

get file info similar to C's runtime library, ex, $file_size = (stat ($filename))[7];

unlink (list)

delete files, returns the number of files deleted

Sting Functions

chomp (list)

remove newline from end of each element

chop (list)

remove last character from each element

eval (expr)

expr is parsed and executed as if it were a Perl program. If there is a syntax or runtime error, an undefined string is returned by eval() and $@ is set to the error message between {}

length (expr)

return length in characters

substr (expr, offset [, len])

extract a substring of length len out of expr and return it

Array Functions

grep (expr, list)

expr can be a regex

join (expr, list)

returns list joined by expr

keys (%hash)

return the keys in a hash in no particular order

pop (@array)

pops off and returns the last value of the array

push (@array, list)

pushes the value of list onto the end of the erray

shift (@array)

shifts the first value of the array off and returns it, shortening the array by 1 and moving everything down

sort (list)

sorts the list and returns it

splice (@array, offset [, length [, list] ])

removes the elements of @array designated by offset and length and replaces them with list, and returns elements removed

split ([pattern [, expr [, limit ] ] ])

splits a string into an array of strings and returns it. If limit is specified, splits into at most that number. If pattern is omitted, splits at the whitespace. If not in an array context, returns number of fields and splits to @_.

Subroutines, Packages and Modules

package name

designates the remainder of the current block as a package

require expr

if expr is numeric, requires Perl to be at least that version (use this if you are using functionality of a specific version, eg, references in perl 5), otherwise expr must be the name of a file

return expr

returns from a subroutine with the value specified

use name [ [version] list]

imports semantics from the named module into the current package

System Interaction

chdir [list]

changes the working directory Note: This only works in the context of the script. Once the script exits, you are in the directory you started from.

die [list]

prints values of list to STDERR

exit [expr]

exits immediately with the value of expr

fork

does a fork(2) system call and returns the PID of the child to the parent and zero to the child process

kill [list]

sends a signal to a list of processes, the first element of the list must be the signal to send

sleep [expr]

causes the program to sleep for expr seconds

warn [list]

prints a message to STDERR like die() but does not exit

Miscellaneous

defined (expr)

test whether the lvalue expr has an actual value

Networking and UNIX Specific Functions