Perl Functions References

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Here is the list of all important functions supported by standard Perl. Click over a function to find its detail.

  • abs - absolute value function

  • accept - accept an incoming socket connect

  • alarm - schedule a SIGALRM

  • atan2 - arctangent of Y/X in the range -PI to PI

  • bind - binds an address to a socket

  • binmode - prepare binary files for I/O

  • bless - create an object

  • caller - get context of the current subroutine call

  • chdir - change your current working directory

  • chmod - changes the permissions on a list of files

  • chomp - remove a trailing record separator from a string

  • chop - remove the last character from a string

  • chown - change the owership on a list of files

  • chr - get character this number represents

  • chroot - make directory new root for path lookups

  • close - close file (or pipe or socket) handle

  • closedir - close directory handle

  • connect - connect to a remote socket

  • continue - optional trailing block in a while or foreach

  • cos - cosine function

  • crypt - one-way passwd-style encryption

  • dbmclose - breaks binding on a tied dbm file

  • dbmopen - create binding on a tied dbm file

  • defined - test whether a value, variable, or function is defined or not

  • delete - deletes a value from a hash

  • die - raise an exception or bail out

  • do - turn a BLOCK into a TERM

  • dump - create an immediate core dump

  • each - retrieve the next key/value pair from a hash

  • endgrent - be done using group file

  • endhostent - be done using hosts file

  • endnetent - be done using networks file

  • endprotoent - be done using protocols file

  • endpwent - be done using passwd file

  • endservent - be done using services file

  • eof - test a filehandle for its end

  • eval - catch exceptions or compile and run code

  • exec - abandon this program to run another

  • exists - test whether a hash key is present

  • exit - terminate this program

  • exp - raise I to a power

  • fcntl - file control system call

  • fileno - return file descriptor from filehandle

  • flock - lock an entire file with an advisory lock

  • fork - create a new process just like this one

  • format - declare a picture format with use by the write() function

  • formline - internal function used for formats

  • getc - get the next character from the filehandle

  • getgrent - get next group record

  • getgrgid - get group record given group user ID

  • getgrnam - get group record given group name

  • gethostbyaddr - get host record given its address

  • gethostbyname - get host record given name

  • gethostent - get next hosts record

  • getlogin - return who logged in at this tty

  • getnetbyaddr - get network record given its address

  • getnetbyname - get networks record given name

  • getnetent - get next networks record

  • getpeername - find the other end of a socket connection

  • getpgrp - get process group

  • getppid - get parent process ID

  • getpriority - get current nice value

  • getprotobyname - get protocol record given name

  • getprotobynumber - get protocol record numeric protocol

  • getprotoent - get next protocols record

  • getpwent - get next passwd record

  • getpwnam - get passwd record given user login name

  • getpwuid - get passwd record given user ID

  • getservbyname - get services record given its name

  • getservbyport - get services record given numeric port

  • getservent - get next services record

  • getsockname - retrieve the sockaddr for a given socket

  • getsockopt - get socket options on a given socket

  • glob - expand filenames using wildcards

  • gmtime - convert UNIX time into record or string using Greenwich time format.

  • goto - create spaghetti code

  • grep - locate elements in a list test true against a given criterion

  • hex - convert a string to a hexadecimal number

  • import - patch a module's namespace into your own

  • index - find a substring within a string

  • int - get the integer portion of a number

  • ioctl - system-dependent device control system call

  • join - join a list into a string using a separator

  • keys - retrieve list of indices from a hash

  • kill - send a signal to a process or process group

  • last - exit a block prematurely

  • lc - return lower-case version of a string

  • lcfirst - return a string with just the next letter in lower case

  • length - return the number of bytes in a string

  • link - create a hard link in the filesytem

  • listen - register your socket as a server

  • local - create a temporary value for a global variable (dynamic scoping)

  • localtime - convert UNIX time into record or string using local time

  • lock - get a thread lock on a variable, subroutine, or method

  • log - retrieve the natural logarithm for a number

  • lstat - stat a symbolic link

  • m - match a string with a regular expression pattern

  • map - apply a change to a list to get back a new list with the changes

  • mkdir - create a directory

  • msgctl - SysV IPC message control operations

  • msgget - get SysV IPC message queue

  • msgrcv - receive a SysV IPC message from a message queue

  • msgsnd - send a SysV IPC message to a message queue

  • my - declare and assign a local variable (lexical scoping)

  • next - iterate a block prematurely

  • no - unimport some module symbols or semantics at compile time

  • oct - convert a string to an octal number

  • open - open a file, pipe, or descriptor

  • opendir - open a directory

  • ord - find a character's numeric representation

  • our - declare and assign a package variable (lexical scoping)

  • pack - convert a list into a binary representation

  • package - declare a separate global namespace

  • pipe - open a pair of connected filehandles

  • pop - remove the last element from an array and return it

  • pos - find or set the offset for the last/next m//g search

  • print - output a list to a filehandle

  • printf - output a formatted list to a filehandle

  • prototype - get the prototype (if any) of a subroutine

  • push - append one or more elements to an array

  • q - singly quote a string

  • qq - doubly quote a string

  • qr - Compile pattern

  • quotemeta - quote regular expression magic characters

  • qw - quote a list of words

  • qx - backquote quote a string

  • rand - retrieve the next pseudorandom number

  • read - fixed-length buffered input from a filehandle

  • readdir - get a directory from a directory handle

  • readline - fetch a record from a file

  • readlink - determine where a symbolic link is pointing

  • readpipe - execute a system command and collect standard output

  • recv - receive a message over a Socket

  • redo - start this loop iteration over again

  • ref - find out the type of thing being referenced

  • rename - change a filename

  • require - load in external functions from a library at runtime

  • reset - clear all variables of a given name

  • return - get out of a function early

  • reverse - flip a string or a list

  • rewinddir - reset directory handle

  • rindex - right-to-left substring search

  • rmdir - remove a directory

  • s - replace a pattern with a string

  • scalar - force a scalar context

  • seek - reposition file pointer for random-access I/O

  • seekdir - reposition directory pointer

  • select - reset default output or do I/O multiplexing

  • semctl - SysV semaphore control operations

  • semget - get set of SysV semaphores

  • semop - SysV semaphore operations

  • send - send a message over a socket

  • setgrent - prepare group file for use

  • sethostent - prepare hosts file for use

  • setnetent - prepare networks file for use

  • setpgrp - set the process group of a process

  • setpriority - set a process's nice value

  • setprotoent - prepare protocols file for use

  • setpwent - prepare passwd file for use

  • setservent - prepare services file for use

  • setsockopt - set some socket options

  • shift - remove the first element of an array, and return it

  • shmctl - SysV shared memory operations

  • shmget - get SysV shared memory segment identifier

  • shmread - read SysV shared memory

  • shmwrite - write SysV shared memory

  • shutdown - close down just half of a socket connection

  • sin - return the sine of a number

  • sleep - block for some number of seconds

  • socket - create a socket

  • socketpair - create a pair of sockets

  • sort - sort a list of values

  • splice - add or remove elements anywhere in an array

  • split - split up a string using a regexp delimiter

  • sprintf - formatted print into a string

  • sqrt - square root function

  • srand - seed the random number generator

  • stat - get a file's status information

  • study - optimize input data for repeated searches

  • sub - declare a subroutine, possibly anonymously

  • substr - get or alter a portion of a stirng

  • symlink - create a symbolic link to a file

  • syscall - execute an arbitrary system call

  • sysopen - open a file, pipe, or descriptor

  • sysread - fixed-length unbuffered input from a filehandle

  • sysseek - position I/O pointer on handle used with sysread and syswrite

  • system - run a separate program

  • syswrite - fixed-length unbuffered output to a filehandle

  • tell - get current seekpointer on a filehandle

  • telldir - get current seekpointer on a directory handle

  • tie - bind a variable to an object class

  • tied - get a reference to the object underlying a tied variable

  • time - return number of seconds since 1970

  • times - return elapsed time for self and child processes

  • tr - transliterate a string

  • truncate - shorten a file

  • uc - return upper-case version of a string

  • ucfirst - return a string with just the next letter in upper case

  • umask - set file creation mode mask

  • undef - remove a variable or function definition

  • unlink - remove one link to a file

  • unpack - convert binary structure into normal perl variables

  • unshift - prepend more elements to the beginning of a list

  • untie - break a tie binding to a variable

  • use - load in a module at compile time

  • utime - set a file's last access and modify times

  • values - return a list of the values in a hash

  • vec - test or set particular bits in a string

  • wait - wait for any child process to die

  • waitpid - wait for a particular child process to die

  • wantarray - get void vs scalar vs list context of current subroutine call

  • warn - print debugging info

  • write - print a picture record

  • -X - a file test (-r, -x, etc)

  • y - transliterate a string



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