NAME

Sidef::Sys::Sys - System-level operations and utilities

DESCRIPTION

The Sys class provides an interface to various system-level operations, including process control, I/O operations, user/group management, network queries, and other low-level system functions. This class wraps many Perl built-in functions and provides a Sidef-friendly interface to system programming capabilities.

SYNOPSIS

# Process control
var pid = Sys.fork
Sys.sleep(2)
Sys.exit(0)

# I/O operations
Sys.say("Hello, World!")
var input = Sys.readln("Enter your name: ")
Sys.printf("Welcome, %s!\n", input)

# System information
say Sys.os           # Operating system name
say Sys.user         # Current username

# File operations
Sys.open(var fh, '<', 'file.txt')
Sys.opendir(var dh, '/tmp')

# User/group information
var user_info = Sys.getpwnam('root')
var group_info = Sys.getgrnam('wheel')

INHERITS

Inherits methods from:

* Sidef::Object::Object

METHODS

alarm

Sys.alarm(sec)

Schedules a SIGALRM signal to be delivered to the process after the specified number of seconds. Returns the number of seconds remaining from any previously set alarm. Setting sec to 0 cancels any pending alarm.

Sys.alarm(10)  # Set alarm for 10 seconds
Sys.alarm(0)   # Cancel alarm

bless

Sys.bless(obj, class)

Blesses an object into the specified class, changing its type. This is used for creating objects of specific classes. Returns the blessed object.

var obj = Hash()
Sys.bless(obj, :MyClass)

class_name

Sys.class_name(obj)

Returns the class name (type) of the given object as a string.

say Sys.class_name(42)        # "Number"
say Sys.class_name("hello")   # "String"
say Sys.class_name([1,2,3])   # "Array"

defined

Sys.defined(obj)

Returns true if the object is defined (not nil), false otherwise. This is useful for checking whether a variable has been assigned a value.

say Sys.defined(nil)      # false
say Sys.defined(0)        # true
say Sys.defined("")       # true

die

Sys.die(*args)

Raises a fatal exception with the specified message and terminates the program unless caught by an eval or try-catch block. The arguments are concatenated to form the error message.

Sys.die("Fatal error occurred!")
Sys.die("Error: ", error_msg, " at line ", line_num)

Aliases: raise

eval

Sys.eval(code)

Evaluates a string as Sidef code and returns the result. If an error occurs during evaluation, it returns nil and sets the error in STDERR.

var result = Sys.eval("2 + 2")  # 4
var result = Sys.eval("say 'Hello'")

exec

Sys.exec(*args)

Executes an external command, replacing the current process. This function does not return on success. Arguments can be a single string or a list of command and arguments.

Sys.exec("ls", "-la", "/tmp")
Sys.exec("echo 'Hello World'")

exit

Sys.exit(code)

Terminates the program immediately with the specified exit code. An exit code of 0 typically indicates success, while non-zero values indicate various error conditions.

Sys.exit(0)     # Success
Sys.exit(1)     # Error

fork

Sys.fork

Creates a child process. Returns the child process ID (PID) to the parent process, 0 to the child process, or nil on failure.

var pid = Sys.fork
if (pid == 0) {
    say "I am the child"
    Sys.exit(0)
}
else {
    say "I am the parent, child PID: #{pid}"
    Sys.wait
}

getgrent

Sys.getgrent

Returns the next group entry from the system group database. Returns nil when there are no more entries. Must be reset with setgrent() to iterate again.

Sys.setgrent
while (var group = Sys.getgrent) {
    say group
}

getgrgid

Sys.getgrgid(gid)

Returns group information for the specified group ID (GID). Returns a hash containing group details including name, password, gid, and members.

var group = Sys.getgrgid(0)
say group{:name}     # Usually "root" or "wheel"

getgrnam

Sys.getgrnam(name)

Returns group information for the specified group name. Returns a hash containing group details including name, password, gid, and members.

var group = Sys.getgrnam('wheel')
say group{:gid}

gethostbyaddr

Sys.gethostbyaddr(addr, addrtype)

Returns host information for the specified network address. The addrtype parameter specifies the address family (typically 2 for AF_INET).

var host = Sys.gethostbyaddr("127.0.0.1", 2)

gethostbyname

Sys.gethostbyname(name)

Returns host information for the specified hostname. Returns a hash containing name, aliases, addrtype, and addresses.

var host = Sys.gethostbyname('localhost')
say host{:name}

gethostent

Sys.gethostent

Returns the next host entry from the system hosts database. Returns nil when there are no more entries.

getnetbyaddr

Sys.getnetbyaddr(addr, addrtype)

Returns network information for the specified network address and address type.

getnetbyname

Sys.getnetbyname(name)

Returns network information for the specified network name.

var net = Sys.getnetbyname('loopback')

getnetent

Sys.getnetent

Returns the next network entry from the system networks database. Returns nil when there are no more entries.

getpgrp

Sys.getpgrp(pid)

Returns the process group ID for the specified process ID. If pid is 0 or nil, returns the process group of the current process.

var pgrp = Sys.getpgrp(0)  # Current process group

getppid

Sys.getppid

Returns the process ID (PID) of the parent process.

say "My parent PID is: ", Sys.getppid

getpriority

Sys.getpriority(which, who)

Returns the priority (nice value) of a process, process group, or user. The which parameter specifies the type (0=process, 1=process group, 2=user), and who specifies the ID.

var priority = Sys.getpriority(0, 0)  # Current process priority

getprotobyname

Sys.getprotobyname(name)

Returns protocol information for the specified protocol name (e.g., 'tcp', 'udp', 'icmp').

var proto = Sys.getprotobyname('tcp')
say proto{:proto}  # Protocol number

getprotobynumber

Sys.getprotobynumber(num)

Returns protocol information for the specified protocol number.

var proto = Sys.getprotobynumber(6)  # TCP

getprotoent

Sys.getprotoent

Returns the next protocol entry from the system protocols database. Returns nil when there are no more entries.

getpwent

Sys.getpwent

Returns the next user entry from the system password database. Returns nil when there are no more entries. Must be reset with setpwent() to iterate again.

Sys.setpwent
while (var user = Sys.getpwent) {
    say user{:name}
}

getpwnam

Sys.getpwnam(name)

Returns user information for the specified username. Returns a hash containing name, passwd, uid, gid, gecos, dir, and shell.

var user = Sys.getpwnam('root')
say user{:uid}
say user{:dir}

getpwuid

Sys.getpwuid(uid)

Returns user information for the specified user ID (UID). Returns a hash containing name, passwd, uid, gid, gecos, dir, and shell.

var user = Sys.getpwuid(1000)
say user{:name}

getservbyname

Sys.getservbyname(name, proto)

Returns service information for the specified service name and protocol.

var service = Sys.getservbyname('http', 'tcp')
say service{:port}  # 80

getservbyport

Sys.getservbyport(port, proto)

Returns service information for the specified port number and protocol.

var service = Sys.getservbyport(80, 'tcp')
say service{:name}  # "http"

getservent

Sys.getservent

Returns the next service entry from the system services database. Returns nil when there are no more entries.

isweak

Sys.isweak(obj)

Returns true if the reference to the object is weak (will not prevent garbage collection), false otherwise.

var ref = \obj
say Sys.isweak(ref)  # false
Sys.weaken(ref)
say Sys.isweak(ref)  # true

kill

Sys.kill(signal, *list)

Sends the specified signal to the list of process IDs. Returns the number of processes successfully signaled. Signal can be a number or a name (e.g., 'TERM', 'KILL', 'HUP').

Sys.kill('TERM', 1234)        # Terminate process 1234
Sys.kill(9, 1234, 5678)       # Kill multiple processes
Sys.kill('HUP', Sys.getppid)  # Send HUP to parent

nano_sleep

Sys.nano_sleep(sec)

Suspends execution for the specified number of seconds with nanosecond precision. Unlike sleep(), this accepts fractional seconds.

Sys.nano_sleep(0.5)       # Sleep for 500 milliseconds
Sys.nano_sleep(1.25)      # Sleep for 1.25 seconds

Aliases: nanosleep

open

Sys.open(var, mode, filename)

Opens a file and assigns the file handle to the specified variable. Mode can be '<' (read), '>' (write), '>>' (append), '+<' (read/write), etc. Returns true on success, false on failure.

Sys.open(var fh, '<', 'input.txt') && do {
    say fh.readline
    fh.close
}

opendir

Sys.opendir(var, dirname)

Opens a directory and assigns the directory handle to the specified variable. Returns true on success, false on failure.

Sys.opendir(var dh, '/tmp') && do {
    while (var entry = dh.read) {
        say entry
    }
    dh.close
}

os

Sys.os

Returns the operating system name as a string (e.g., 'linux', 'darwin', 'MSWin32', 'freebsd').

say Sys.os
if (Sys.os == 'linux') {
    say "Running on Linux"
}

Aliases: osname

print

Sys.print(*args)

Prints the arguments to the currently selected output filehandle (default STDOUT) without appending a newline. Returns true.

Sys.print("Hello")
Sys.print("Value: ", value, " at ", timestamp)

printf

Sys.printf(*args)

Formats and prints output according to a format string (first argument) to the currently selected output filehandle. Uses sprintf-style formatting.

Sys.printf("Value: %d, Name: %s\n", 42, "Alice")
Sys.printf("%.2f%%\n", percentage)

printh

Sys.printh(fh, *args)

Prints the arguments to the specified filehandle without appending a newline. Returns true.

Sys.open(var fh, '>', 'output.txt')
Sys.printh(fh, "Line 1")
Sys.printh(fh, "Line 2")
fh.close

read

Sys.read(type, opt_arg)

Reads input from STDIN based on the specified type. The type parameter determines what kind of input to read, and opt_arg provides additional options.

var line = Sys.read(:line)
var char = Sys.read(:char)

readln

Sys.readln(text)

Reads a line of input from STDIN, optionally displaying a prompt first. Returns the input string without the trailing newline.

var name = Sys.readln("Enter your name: ")
var age = Sys.readln("Enter your age: ")

Aliases: scanln, readline

ref

Sys.ref(obj)

Returns a reference to the object. This creates a reference that can be dereferenced later.

var x = 42
var r = Sys.ref(x)
say *r  # Dereference: 42

refaddr

Sys.refaddr(obj)

Returns the memory address of the reference as a number. This is useful for debugging and understanding object identity.

var obj = [1, 2, 3]
say Sys.refaddr(obj)  # e.g., 140234567890123

reftype

Sys.reftype(obj)

Returns the reference type of the object as a string (e.g., 'ARRAY', 'HASH', 'SCALAR', 'CODE').

say Sys.reftype([1,2,3])    # "ARRAY"
say Sys.reftype({a:1})      # "HASH"

run

Sys.run(*args)

Executes an external command and waits for it to complete. Returns true if the command succeeded (exit status 0), false otherwise. Output is displayed to STDOUT/STDERR.

Sys.run("ls", "-la")
Sys.run("echo 'Hello World'")

if (Sys.run("command")) {
    say "Command succeeded"
}

Aliases: s

say

Sys.say(*args)

Prints the arguments to the currently selected output filehandle (default STDOUT) and appends a newline. Returns true.

Sys.say("Hello, World!")
Sys.say("Value: ", value)
Sys.say()  # Print empty line

Aliases: println

select

Sys.select(fh)

Sets the specified filehandle as the default output filehandle for print, printf, say, etc. Returns the previously selected filehandle.

Sys.open(var fh, '>', 'output.txt')
var old = Sys.select(fh)
say "This goes to the file"
Sys.select(old)
say "This goes to STDOUT"

setgrent

Sys.setgrent

Resets the group database iterator to the beginning, allowing getgrent() to iterate from the start again.

Sys.setgrent
while (var group = Sys.getgrent) {
    # Process groups
}

sethostent

Sys.sethostent(stayopen)

Opens and rewinds the hosts database. If stayopen is true, the database connection remains open for efficiency.

setnetent

Sys.setnetent(stayopen)

Opens and rewinds the networks database. If stayopen is true, the database connection remains open for efficiency.

setpgrp

Sys.setpgrp(pid, pgrp)

Sets the process group for the specified process ID. Both parameters of 0 set the process group of the current process.

Sys.setpgrp(0, 0)  # Set current process as process group leader

setpriority

Sys.setpriority(which, who, priority)

Sets the priority (nice value) of a process, process group, or user. The which parameter specifies the type (0=process, 1=process group, 2=user), who specifies the ID, and priority is the new priority value (-20 to 20, where lower numbers mean higher priority).

Sys.setpriority(0, 0, 10)  # Lower priority of current process

setprotoent

Sys.setprotoent(stayopen)

Opens and rewinds the protocols database. If stayopen is true, the database connection remains open for efficiency.

setpwent

Sys.setpwent

Resets the password database iterator to the beginning, allowing getpwent() to iterate from the start again.

Sys.setpwent
while (var user = Sys.getpwent) {
    # Process users
}

setservent

Sys.setservent(stayopen)

Opens and rewinds the services database. If stayopen is true, the database connection remains open for efficiency.

sidef

Sys.sidef

Returns the version of the Sidef interpreter as a string.

say "Sidef version: ", Sys.sidef

sleep

Sys.sleep(sec)

Suspends execution for the specified number of seconds (integer). For fractional seconds, use nano_sleep() or usleep().

Sys.sleep(5)   # Sleep for 5 seconds
Sys.sleep(1)   # Sleep for 1 second

stderr

Sys.stderr

Returns the standard error filehandle (STDERR). This can be used for error output and diagnostics.

Sys.stderr.say("Error message")
Sys.printh(Sys.stderr, "Warning: ")

stdin

Sys.stdin

Returns the standard input filehandle (STDIN). This can be used for reading input.

var line = Sys.stdin.readline
while (var line = Sys.stdin.readline) {
    say line
}

stdout

Sys.stdout

Returns the standard output filehandle (STDOUT). This can be used for explicit output operations.

Sys.stdout.say("Hello")
Sys.printh(Sys.stdout, "Output")

ualarm

Sys.ualarm(sec)

Schedules a SIGALRM signal to be delivered after the specified number of microseconds. Returns the number of microseconds remaining from any previously set alarm. This provides finer granularity than alarm().

Sys.ualarm(500000)  # Alarm in 500,000 microseconds (0.5 seconds)

Aliases: micro_alarm

umask

Sys.umask(mode)

Sets the file creation mask (umask) and returns the previous mask. The umask determines the default permissions for newly created files and directories.

var old = Sys.umask(0o022)  # Set umask to 022 (octal)
# Create files...
Sys.umask(old)              # Restore old umask

unweaken

Sys.unweaken(obj)

Converts a weak reference back to a strong reference, preventing the object from being garbage collected if this is the only reference.

var ref = \obj
Sys.weaken(ref)
Sys.unweaken(ref)  # Now strong again

user

Sys.user

Returns the username of the current user as a string.

say "Current user: ", Sys.user

Aliases: getlogin

usleep

Sys.usleep(sec)

Suspends execution for the specified number of microseconds.

Sys.usleep(500000)     # Sleep for 500,000 microseconds (0.5 seconds)
Sys.usleep(1000000)    # Sleep for 1,000,000 microseconds (1 second)

Aliases: micro_sleep

wait

Sys.wait

Waits for a child process to terminate and returns the process ID of the terminated child, or -1 if there are no child processes. The exit status can be retrieved from the $? variable.

var pid = Sys.fork
if (pid == 0) {
    # Child process
    Sys.exit(0)
}
else {
    # Parent process
    var terminated_pid = Sys.wait
    say "Child #{terminated_pid} terminated"
}

warn

Sys.warn(*args)

Prints a warning message to STDERR. The arguments are concatenated to form the warning message. Unlike die(), this does not terminate the program.

Sys.warn("Warning: low disk space")
Sys.warn("Deprecated function used at line ", line_num)

weaken

Sys.weaken(obj)

Converts a reference to a weak reference. Weak references do not prevent the referenced object from being garbage collected.

var obj = [1, 2, 3]
var ref = \obj
Sys.weaken(ref)
# obj can now be garbage collected even though ref exists

AUTHOR

Daniel Șuteu, <trizen@cpan.org>

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.16.0 or, at your option, any later version of Perl 5 you may have available.

To install Sidef, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Sidef

CPAN shell

perl -MCPAN -e shell
install Sidef

For more information on module installation, please visit the detailed CPAN module installation guide.

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