The following variables define the standard channels.
stdin : InChannel
The standard input channel, open for reading.
stdout : OutChannel
The standard output channel, open for writing.
stderr : OutChannel
The standard error channel, open for writing.
The fopen function opens a file for reading or writing.
$(fopen file, mode) : Channel
file : File
mode : String
The file is the name of the file to be opened. The mode is a combination of the following characters.
Binary mode is not significant on Unix systems, where text and binary modes are equivalent.
$(close channel...)
channel : Channel
The close function closes a file that was previously opened with fopen.
$(read channel, amount) : String
channel : InChannel
amount : Int
raises RuntimeException
The read function reads up to amount bytes from an input channel, and returns the data that was read. If an end-of-file condition is reached, the function raises a RuntimeException exception.
$(write channel, buffer, offset, amount) : String
channel : OutChannel
buffer : String
offset : Int
amount : Int
$(write channel, buffer) : String
channel : OutChannel
buffer : String
raises RuntimeException
In the 4-argument form, the write function writes bytes to the output channel channel from the buffer, starting at position offset. Up to amount bytes are written. The function returns the number of bytes that were written.
The 3-argument form is similar, but the offset is 0.
In the 2-argument form, the offset is 0, and the amount if the length of the buffer.
If an end-of-file condition is reached, the function raises a RuntimeException exception.
$(lseek channel, offset, whence) : Int
channel : Channel
offset : Int
whence : String
raises RuntimeException
The lseek function repositions the offset of the channel channel according to the whence directive, as follows:
The lseek function returns the new position in the file.
rewind(channel...)
channel : Channel
The rewind function set the current file position to the beginning of the file.
$(tell channel...) : Int...
channel : Channel
raises RuntimeException
The tell function returns the current position of the channel.
$(flush channel...)
channel : OutChannel
The flush function can be used only on files that are open for writing. It flushes all pending data to the file.
$(dup channel) : Channel
channel : Channel
raises RuntimeException
The dup function returns a new channel referencing the same file as the argument.
dup2(channel1, channel2)
channel1 : Channel
channel2 : Channel
raises RuntimeException
The dup2 function causes channel2 to refer to the same file as channel1.
set-nonblock-mode(mode, channel...)
channel : Channel
mode : String
The set-nonblock-mode function sets the nonblocking flag on the given channel. When IO is performed on the channel, and the operation cannot be completed immediately, the operations raises a RuntimeException.
set-close-on-exec-mode(mode, channel...)
channel : Channel
mode : String
raises RuntimeException
The set-close-on-exec-mode function sets the close-on-exec flags for the given channels. If the close-on-exec flag is set, the channel is not inherited by child processes. Otherwise it is.
$(pipe) : Pipe raises RuntimeException
The pipe function creates a Pipe object, which has two fields. The read field is a channel that is opened for reading, and the write field is a channel that is opened for writing.
mkfifo(mode, node...)
mode : Int
node : Node
The mkfifo function creates a named pipe.
$(select rfd..., wfd..., wfd..., timeout) : Select
rfd : InChannel
wfd : OutChannel
efd : Channel
timeout : float
raises RuntimeException
The select function polls for possible IO on a set of channels. The rfd are a sequence of channels for reading, wfd are a sequence of channels for writing, and efd are a sequence of channels to poll for error conditions. The timeout specifies the maximum amount of time to wait for events.
On successful return, select returns a Select object, which has the following fields:
lockf(channel, command, len)
channel : Channel
command : String
len : Int
raises RuntimeException
The lockf function places a lock on a region of the channel. The region starts at the current position and extends for len bytes.
The possible values for command are the following.
The InetAddr object describes an Internet address. It contains the following fields.
A Host object contains the following fields.
$(gethostbyname host...) : Host...
host : String
raises RuntimeException
The gethostbyname function returns a Host object for the specified host. The host may specify a domain name or an Internet address.
The Protocol object represents a protocol entry. It has the following fields.
$(getprotobyname name...) : Protocol...
name : Int or String
raises RuntimeException
The getprotobyname function returns a Protocol object for the specified protocol. The name may be a protocol name, or a protocol number.
The Service object represents a network service. It has the following fields.
$(getservbyname service...) : Service...
service : String or Int
raises RuntimeException
The getservbyname function gets the information for a network service. The service may be specified as a service name or number.
$(socket domain, type, protocol) : Channel
domain : String
type : String
protocol : String
raises RuntimeException
The socket function creates an unbound socket.
The possible values for the arguments are as follows.
The domain may have the following values.
The type may have the following values.
The protocol is an Int or String that specifies a protocol in the protocols database.
bind(socket, host, port)
socket : InOutChannel
host : String
port : Int
bind(socket, file)
socket : InOutChannel
file : File
raise RuntimeException
The bind function binds a socket to an address.
The 3-argument form specifies an Internet connection, the host specifies a host name or IP address, and the port is a port number.
The 2-argument form is for Unix sockets. The file specifies the filename for the address.
listen(socket, requests)
socket : InOutChannel
requests : Int
raises RuntimeException
The listen function sets up the socket for receiving up to requests number of pending connection requests.
$(accept socket) : InOutChannel
socket : InOutChannel
raises RuntimeException
The accept function accepts a connection on a socket.
connect(socket, addr, port)
socket : InOutChannel
addr : String
port : int
connect(socket, name)
socket : InOutChannel
name : File
raise RuntimeException
The connect function connects a socket to a remote address.
The 3-argument form specifies an Internet connection. The addr argument is the Internet address of the remote host, specified as a domain name or IP address. The port argument is the port number.
The 2-argument form is for Unix sockets. The name argument is the filename of the socket.
$(getc) : String
$(getc file) : String
file : InChannel or File
raises RuntimeException
The getc function returns the next character of a file. If the argument is not specified, stdin is used as input. If the end of file has been reached, the function returns false.
$(gets) : String
$(gets channel) : String
channel : InChannel or File
raises RuntimeException
The gets function returns the next line from a file. The function returns the empty string if the end of file has been reached. The line terminator is removed.
$(fgets) : String
$(fgets channel) : String
channel : InChannel or File
raises RuntimeException
The fgets function returns the next line from a file that has been opened for reading with fopen. The function returns the empty string if the end of file has been reached. The returned string is returned as literal data. The line terminator is not removed.
Output is printed with the print and println functions. The println function adds a terminating newline to the value being printed, the print function does not.
fprint(<file>, <string>)
print(<string>)
eprint(<string>)
fprintln(<file>, <string>)
println(<string>)
eprintln(<string>)
The fprint functions print to a file that has been previously opened with fopen. The print functions print to the standard output channel, and the eprint functions print to the standard error channel.
Values can be printed with the printv and printvln functions. The printvln function adds a terminating newline to the value being printed, the printv function does not.
fprintv(<file>, <string>)
printv(<string>)
eprintv(<string>)
fprintvln(<file>, <string>)
printvln(<string>)
eprintvln(<string>)
The fprintv functions print to a file that has been previously opened with fopen. The printv functions print to the standard output channel, and the eprintv functions print to the standard error channel.
Many of the higher-level functions use regular expressions. Regular expressions are defined by strings with syntax nearly identical to awk(1).
Strings may contain the following character constants.
Regular expressions are defined using the special characters .\^$[(){}*?+.
Character classes can be used to specify character sequences abstractly. Some of these sequences can change depending on your LOCALE.
cat(files) : Sequence
files : File or InChannel Sequence
The cat function concatenates the output from multiple files and returns it as a string.
grep(pattern) : String # input from stdin, default options
pattern : String
grep(pattern, files) : String # default options
pattern : String
files : File Sequence
grep(options, pattern, files) : String
options : String
pattern : String
files : File Sequence
The grep function searches for occurrences of a regular expression pattern in a set of files, and prints lines that match. This is like a highly-simplified version of grep(1).
The options are:
The pattern is a regular expression.
If successful (grep found a match), the function returns true. Otherwise, it returns false.
awk(input-files)
case pattern1:
body1
case pattern2:
body2
...
default:
bodyd
The awk function provides input processing similar to awk(1), but more limited. The function takes filename arguments. If called with no arguments, the input is taken from stdin. If arguments are provided, each specifies an InChannel, or the name of a file for input. Output is always to stdout.
The variables RS and FS define record and field separators as regular expressions. The default value of RS is the regular expression \r| |\r . The default value of FS is the regular expression [ \t]+.
The awk function operates by reading the input one record at a time, and processing it according to the following algorithm.
For each line, the record is first split into fields using the field separator FS, and the fields are bound to the variables $1, $2, .... The variable $0 is defined to be the entire line, and $* is an array of all the field values. The $(NF) variable is defined to be the number of fields.
Next, the cases are evaluated in order. For each case, if the regular expression pattern_i matches the record $0, then body_i is evaluated. If the body ends in an export, the state is passed to the next clause. Otherwise the value is discarded. If the regular expression contains \(r\) expression, those expression override the fields $1, $2, ....
For example, here is an awk function to print the text between two delimiters \begin{<name>} and \end{<name>}, where the <name> must belong to a set passed as an argument to the filter function.
filter(names) =
print = false
awk(A. maximum amount of time to wait for events.
On successful return, select returns a Select object,
which has the following fields:
lockf(channel, command, len)
channel : Channel
command : String
len : Int
raises RuntimeException
The lockf function places a lock on a region of the channel. The region starts at the current position and extends for len bytes.
The possible values for command are the following.
The InetAddr object describes an Internet address. It contains the following fields.
A Host object contains the following fields.
$(gethostbyname host...) : Host...
host : String
raises RuntimeException
The gethostbyname function returns a Host object for the specified host. The host may specify a domain name or an Internet address.
The Protocol object represents a protocol entry. It has the following fields.
$(getprotobyname name...) : Protocol...
name : Int or String
raises RuntimeException
The getprotobyname function returns a Protocol object for the specified protocol. The name may be a protocol name, or a protocol number.
The Service object represents a network service. It has the following fields.
$(getservbyname service...) : Service...
service : String or Int
raises RuntimeException
The getservbyname function gets the information for a network service. The service may be specified as a service name or number.
$(socket domain, type, protocol) : Channel
domain : String
type : String
protocol : String
raises RuntimeException
The socket function creates an unbound socket.
The possible values for the arguments are as follows.
The domain may have the following values.
The type may have the following values.
The protocol is an Int or String that specifies a protocol in the protocols database.
bind(socket, host, port)
socket : InOutChannel
host : String
port : Int
bind(socket, file)
socket : InOutChannel
file : File
raise RuntimeException
The bind function binds a socket to an address.
The 3-argument form specifies an Internet connection, the host specifies a host name or IP address, and the port is a port number.
The 2-argument form is for Unix sockets. The file specifies the filename for the address.
listen(socket, requests)
socket : InOutChannel
requests : Int
raises RuntimeException
The listen function sets up the socket for receiving up to requests number of pending connection requests.
$(accept socket) : InOutChannel
socket : InOutChannel
raises RuntimeException
The accept function accepts a connection on a socket.
connect(socket, addr, port)
socket : InOutChannel
addr : String
port : int
connect(socket, name)
socket : InOutChannel
name : File
raise RuntimeException
The connect function connects a socket to a remote address.
The 3-argument form specifies an Internet connection. The addr argument is the Internet address of the remote host, specified as a domain name or IP address. The port argument is the port number.
The 2-argument form is for Unix sockets. The name argument is the filename of the socket.
$(getc) : String
$(getc file) : String
file : InChannel or File
raises RuntimeException
The getc function returns the next character of a file. If the argument is not specified, stdin is used as input. If the end of file has been reached, the function returns false.
$(gets) : String
$(gets channel) : String
channel : InChannel or File
raises RuntimeException
The gets function returns the next line from a file. The function returns the empty string if the end of file has been reached. The line terminator is removed.
$(fgets) : String
$(fgets channel) : String
channel : InChannel or File
raises RuntimeException
The fgets function returns the next line from a file that has been opened for reading with fopen. The function returns the empty string if the end of file has been reached. The returned string is returned as literal data. The line terminator is not removed.
Output is printed with the print and println functions. The println function adds a terminating newline to the value being printed, the print function does not.
fprint(<file>, <string>)
print(<string>)
eprint(<string>)
fprintln(<file>, <string>)
println(<string>)
eprintln(<string>)
The fprint functions print to a file that has been previously opened with fopen. The print functions print to the standard output channel, and the eprint functions print to the standard error channel.
Values can be printed with the printv and printvln functions. The printvln function adds a terminating newline to the value being printed, the printv function does not.
fprintv(<file>, <string>)
printv(<string>)
eprintv(<string>)
fprintvln(<file>, <string>)
printvln(<string>)
eprintvln(<string>)
The fprintv functions print to a file that has been previously opened with fopen. The printv functions print to the standard output channel, and the eprintv functions print to the standard error channel.
Many of the higher-level functions use regular expressions. Regular expressions are defined by strings with syntax nearly identical to awk(1).
Strings may contain the following character constants.
Regular expressions are defined using the special characters .\^$[(){}*?+.
Character classes can be used to specify character sequences abstractly. Some of these sequences can change depending on your LOCALE.
cat(files) : Sequence
files : File or InChannel Sequence
The cat function concatenates the output from multiple files and returns it as a string.
grep(pattern) : String # input from stdin, default options
pattern : String
grep(pattern, files) : String # default options
pattern : String
files : File Sequence
grep(options, pattern, files) : String
options : String
pattern : String
files : File Sequence
The grep function searches for occurrences of a regular expression pattern in a set of files, and prints lines that match. This is like a highly-simplified version of grep(1).
The options are:
The pattern is a regular expression.
If successful (grep found a match), the function returns true. Otherwise, it returns false.
awk(input-files)
case pattern1:
body1
case pattern2:
body2
...
default:
bodyd
The awk function provides input processing similar to awk(1), but more limited. The function takes filename arguments. If called with no arguments, the input is taken from stdin. If arguments are provided, each specifies an InChannel, or the name of a file for input. Output is always to stdout.
The variables RS and FS define record and field separators as regular expressions. The default value of RS is the regular expression \r| |\r . The default value of FS is the regular expression [ \t]+.
The awk function operates by reading the input one record at a time, and processing it according to the following algorithm.
For each line, the record is first split into fields using the field separator FS, and the fields are bound to the variables $1, $2, .... The variable $0 is defined to be the entire line, and $* is an array of all the field values. The $(NF) variable is defined to be the number of fields.
Next, the cases are evaluated in order. For each case, if the regular expression pattern_i matches the record $0, then body_i is evaluated. If the body ends in an export, the state is passed to the next clause. Otherwise the value is discarded. If the regular expression contains \(r\) expression, those expression override the fields $1, $2, ....
For example, here is an awk function to print the text between two delimiters \begin{<name>} and \end{<name>}, where the <name> must belong to a set passed as an argument to the filter function.
filter(names) =
print = false
awk(A. maximum amount of time to wait for events.
On successful return, select returns a Select object,
which has the following fields:
lockf(channel, command, len)
channel : Channel
command : String
len : Int
raises RuntimeException
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