Perl 5 version 22.4
documentation
Perl functions by category
Functions for SCALARs or strings
- chomp
- remove a trailing record separator from a string
- chop
- remove the last character from a string
- chr
- get character this number represents
- crypt
- one-way passwd-style encryption
- fc
- return casefolded version of a string
- hex
- convert a hexadecimal string to a number
- index
- find a substring within a string
- 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 characters in a string
- oct
- convert a string to an octal number
- ord
- find a character's numeric representation
- pack
- convert a list into a binary representation
- q/STRING/
- singly quote a string
- qq/STRING/
- doubly quote a string
- reverse
- flip a string or a list
- rindex
- right-to-left substring search
- sprintf
- formatted print into a string
- substr
- get or alter a portion of a string
- tr///
- transliterate a string
- uc
- return upper-case version of a string
- ucfirst
- return a string with just the next letter in upper case
- y///
- transliterate a string
Regular expressions and pattern matching
- m//
- match a string with a regular expression pattern
- pos
- find or set the offset for the last/next m//g search
- qr/STRING/
- compile pattern
- quotemeta
- quote regular expression magic characters
- s///
- replace a pattern with a string
- split
- split up a string using a regexp delimiter
- study
- no-op, formerly optimized input data for repeated searches
Numeric functions
- abs
- absolute value function
- atan2
- arctangent of Y/X in the range -PI to PI
- cos
- cosine function
- exp
- raise I to a power
- hex
- convert a hexadecimal string to a number
- int
- get the integer portion of a number
- log
- retrieve the natural logarithm for a number
- oct
- convert a string to an octal number
- rand
- retrieve the next pseudorandom number
- sin
- return the sine of a number
- sqrt
- square root function
- srand
- seed the random number generator
Functions for real @ARRAYs
- each
- retrieve the next key/value pair from a hash
- keys
- retrieve list of indices from a hash
- pop
- remove the last element from an array and return it
- push
- append one or more elements to an array
- shift
- remove the first element of an array, and return it
- splice
- add or remove elements anywhere in an array
- unshift
- prepend more elements to the beginning of a list
- values
- return a list of the values in a hash
Functions for list data
- grep
- locate elements in a list test true against a given criterion
- join
- join a list into a string using a separator
- map
- apply a change to a list to get back a new list with the changes
- qw/STRING/
- quote a list of words
- reverse
- flip a string or a list
- sort
- sort a list of values
- unpack
- convert binary structure into normal perl variables
Functions for real %HASHes
- delete
- deletes a value from a hash
- each
- retrieve the next key/value pair from a hash
- exists
- test whether a hash key is present
- keys
- retrieve list of indices from a hash
- values
- return a list of the values in a hash
Input and output functions
- binmode
- prepare binary files for I/O
- close
- close file (or pipe or socket) handle
- closedir
- close directory handle
- dbmclose
- breaks binding on a tied dbm file
- dbmopen
- create binding on a tied dbm file
- die
- raise an exception or bail out
- eof
- test a filehandle for its end
- fileno
- return file descriptor from filehandle
- flock
- lock an entire file with an advisory lock
- format
- declare a picture format with use by the write() function
- getc
- get the next character from the filehandle
- print
- output a list to a filehandle
- printf
- output a formatted list to a filehandle
- read
- fixed-length buffered input from a filehandle
- readdir
- get a directory from a directory handle
- readline
- fetch a record from a file
- rewinddir
- reset directory handle
- say
- print with newline
- seek
- reposition file pointer for random-access I/O
- seekdir
- reposition directory pointer
- select
- reset default output or do I/O multiplexing
- syscall
- execute an arbitrary system call
- sysread
- fixed-length unbuffered input from a filehandle
- sysseek
- position I/O pointer on handle used with sysread and syswrite
- syswrite
- fixed-length unbuffered output to a filehandle
- tell
- get current seekpointer on a filehandle
- telldir
- get current seekpointer on a directory handle
- truncate
- shorten a file
- warn
- print debugging info
- write
- print a picture record
Functions for fixed-length data or records
- pack
- convert a list into a binary representation
- read
- fixed-length buffered input from a filehandle
- syscall
- execute an arbitrary system call
- sysread
- fixed-length unbuffered input from a filehandle
- sysseek
- position I/O pointer on handle used with sysread and syswrite
- syswrite
- fixed-length unbuffered output to a filehandle
- unpack
- convert binary structure into normal perl variables
- vec
- test or set particular bits in a string
Functions for filehandles, files, or directories
- -X
- a file test (-r, -x, etc)
- chdir
- change your current working directory
- chmod
- changes the permissions on a list of files
- chown
- change the ownership on a list of files
- chroot
- make directory new root for path lookups
- fcntl
- file control system call
- glob
- expand filenames using wildcards
- ioctl
- system-dependent device control system call
- link
- create a hard link in the filesystem
- lstat
- stat a symbolic link
- mkdir
- create a directory
- open
- open a file, pipe, or descriptor
- opendir
- open a directory
- readlink
- determine where a symbolic link is pointing
- rename
- change a filename
- rmdir
- remove a directory
- select
- reset default output or do I/O multiplexing
- stat
- get a file's status information
- symlink
- create a symbolic link to a file
- sysopen
- open a file, pipe, or descriptor
- umask
- set file creation mode mask
- unlink
- remove one link to a file
- utime
- set a file's last access and modify times
Keywords related to the control flow of your Perl program
- __FILE__
- the name of the current source file
- __LINE__
- the current source line number
- __PACKAGE__
- the current package
- __SUB__
- the current subroutine, or C if not in a subroutine
- break
- break out of a "given" block
- caller
- get context of the current subroutine call
- continue
- optional trailing block in a while or foreach
- die
- raise an exception or bail out
- do
- turn a BLOCK into a TERM
- dump
- create an immediate core dump
- eval
- catch exceptions or compile and run code
- evalbytes
- similar to string eval, but intend to parse a bytestream
- exit
- terminate this program
- goto
- create spaghetti code
- last
- exit a block prematurely
- next
- iterate a block prematurely
- redo
- start this loop iteration over again
- return
- get out of a function early
- sub
- declare a subroutine, possibly anonymously
- wantarray
- get void vs scalar vs list context of current subroutine call
Keywords related to scoping
- caller
- get context of the current subroutine call
- import
- patch a module's namespace into your own
- local
- create a temporary value for a global variable (dynamic scoping)
- my
- declare and assign a local variable (lexical scoping)
- our
- declare and assign a package variable (lexical scoping)
- package
- declare a separate global namespace
- state
- declare and assign a state variable (persistent lexical scoping)
- use
- load in a module at compile time and import its namespace
Miscellaneous functions
- defined
- test whether a value, variable, or function is defined
- formline
- internal function used for formats
- lock
- get a thread lock on a variable, subroutine, or method
- prototype
- get the prototype (if any) of a subroutine
- reset
- clear all variables of a given name
- scalar
- force a scalar context
- undef
- remove a variable or function definition
Functions for processes and process groups
- alarm
- schedule a SIGALRM
- exec
- abandon this program to run another
- fork
- create a new process just like this one
- getpgrp
- get process group
- getppid
- get parent process ID
- getpriority
- get current nice value
- kill
- send a signal to a process or process group
- pipe
- open a pair of connected filehandles
- qx/STRING/
- backquote quote a string
- readpipe
- execute a system command and collect standard output
- setpgrp
- set the process group of a process
- setpriority
- set a process's nice value
- sleep
- block for some number of seconds
- system
- run a separate program
- times
- return elapsed time for self and child processes
- wait
- wait for any child process to die
- waitpid
- wait for a particular child process to die
Keywords related to Perl modules
- do
- turn a BLOCK into a TERM
- import
- patch a module's namespace into your own
- no
- unimport some module symbols or semantics at compile time
- package
- declare a separate global namespace
- require
- load in external functions from a library at runtime
- use
- load in a module at compile time and import its namespace
Keywords related to classes and object-orientation
- bless
- create an object
- dbmclose
- breaks binding on a tied dbm file
- dbmopen
- create binding on a tied dbm file
- package
- declare a separate global namespace
- ref
- find out the type of thing being referenced
- tie
- bind a variable to an object class
- tied
- get a reference to the object underlying a tied variable
- untie
- break a tie binding to a variable
- use
- load in a module at compile time and import its namespace
Low-level socket functions
- accept
- accept an incoming socket connect
- bind
- binds an address to a socket
- connect
- connect to a remote socket
- getpeername
- find the other end of a socket connection
- getsockname
- retrieve the sockaddr for a given socket
- getsockopt
- get socket options on a given socket
- listen
- register your socket as a server
- recv
- receive a message over a Socket
- send
- send a message over a socket
- setsockopt
- set some socket options
- shutdown
- close down just half of a socket connection
- socket
- create a socket
- socketpair
- create a pair of sockets
System V interprocess communication functions
- 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
- semctl
- SysV semaphore control operations
- semget
- get set of SysV semaphores
- semop
- SysV semaphore operations
- shmctl
- SysV shared memory operations
- shmget
- get SysV shared memory segment identifier
- shmread
- read SysV shared memory
- shmwrite
- write SysV shared memory
Fetching user and group info
Fetching network info
Time-related functions
- gmtime
- convert UNIX time into record or string using Greenwich time
- localtime
- convert UNIX time into record or string using local time
- time
- return number of seconds since 1970
- times
- return elapsed time for self and child processes