LuaPosix

Lua Posix

This is a list of the Lua Posix functions. Included is helpful snippets of code. Install lua posix. To get this list do:

require "posix"
for a in pairs(posix) do 
  print(a)
end

access

INPUT

• Path- file or directory path that wants to be checked
• Permission - what permissions do you want to check
  • "r" = read
  • "w" = write
  • "x" = execute
  • "f" = all permissions? not sure

OUPUT

• string - 0 for success, nil for failure if done

bar = require "posix"
temp = bar.access("/etc/passwd", "w")
print(temp)

Will give more information like

bar = require "posix"
print(bar.access("/etc/passwd", "w"))
--If nil will give back the error too
nil     /etc/passwd: Permission denied  13

chdir

INPUT

• Path - where do you want to change directory to

OUPUT

• 0 if success
  • nil if failed

bar = require "posix"
bar.chdir("/etc/")
--print(bar.getcwd()) to see where you are

0 if success, nil if failure. If you

print(bar.chdir("/var/lob"))
-- it will print the system error message also
nil     /var/lob: No such file or directory     2

The access function returns three values altogether; the following example may help to distinguish their use:

lpos = require "posix"
ptr, msg, code = lpos.access("/etc/dhcp")
if ptr == nil then
  print("msg  = " .. msg)
  print("code = " .. code)
else
  print("ptr  = " .. ptr)
end

chmod

INPUT

• PATH - where is the file or directory
  • MODE - what mode to you want to change on the file

OUPUT

• string - 0 if sucess, nil failure

bar = require "posix"
bar.chmod("/etc/passwd", "a=rwx")
--looks like you need to use the ugoa format for this, not numbers

chown

INPUT

• Path-location of file or directory
• UID - User id number
• GID - Group id number

OUPUT

• String - 0 is success and nil for failure

bar = require "posix"
print(bar.chown("/etc/passwd",100,200)
--above will give back nil. Since we printed it will also give back the system errors.

ctermid

INPUT

• NONE- DISPLAYS the terminal id

OUTPUT

• String with the terminal id

bar = require "posix"
print(bar.ctermid())

dir

Directory listing INPUT

• PATH - directory

OUTPUT

• TABLE - table with the file name contents of the directory
  • Failure returns a nil value

bar = require "posix"
bobo = bar.dir("/var/log")
for a,b in ipairs(bobo) do print(b) end
-- the bobo table will output all the file names in /var/log/

errno

Display the error information

INPUT

• NONE

OUPUT

• Success, or Error message

bar = require "posix"
a,b = bar.dir("/var/foo"), bar.errno()
print(a,b)
-- a will be nil or 0, b will be No such file or directory or Success

exec

Replaces the running process with the command specified. Command line arguments are given as additional arguments. (To start a sub process, you probably want fork+exec, not just exec.)

INPUT

• PATH-Location of binary
• ARGs-options to pass to binary

OUTPUT

• Strings

bar = require "posix"
bobo = bar.exec("/bin/ls", "-l", "/etc/")

files

Returns an interator function that loops over each file in the given directory

INPUT

• PATH- Directory

OUPUT

require "posix"

for name in posix.files("/etc") do
    print (name)
end

fork

INPUT

• None

OUTPUT returns: -1 on error, 0 to the child process, and the pid of the child to the parent.

require("posix")

print ("parent: my pid is: " .. posix.getpid("pid")) 

local pid = posix.fork () 

if ( pid == -1 ) then
        print ("parent: The fork failed.")
elseif ( pid == 0 ) then
        print ("child: Hello World! I am pid: " .. posix.getpid("pid") )
        print ("child: I'll sleep for 1 second ... ")
        posix.sleep(1)
        print ("child: Good bye");
else
        print ("parent: While the child sleeps, I'm still running.")
        print ("parent: waiting for child (pid:" .. pid .. ") to die...")
        posix.wait(pid)
        print ("parent: child died, but I'm still alive.")
        print ("parent: Good bye")
end

parent: my pid is: 11050
child: Hello World! I am pid: 11051
child: I'll sleep for 1 second ... 
parent: While the child sleeps, I'm still running.
parent: waiting for child (pid:11051) to die...
child: Good bye
parent: child died, but I'm still alive.
parent: Good bye

getcwd

INPUT

• NONE

OUTPUT

• String- contents of which is the current working directory

bar = require "posix"
print(bar.getcwd())

getenv

INPUT

• NONE

OUPUT

• Table - Current Environment settings

bar = require "posix"
bobo = bar.getenv()
for a,b in pairs(bobo) do print(b) end
-- Varible - Value

getgroup

INPUT

• GID, or groupname

OUPUT

• TABLE -contents of which hold the group name,gid, and users

bar = require "posix"
bobo = bar.getgroup(1000)
for a,b in pairs(bobo) do print(a,b) end
--if you use pairs then bobo will print also the name and gid or the group
--if you use ipairs then just the group members
1 user1
2 user2
name wheel
gid 1

getlogin

Couldn't get it to work

INPUT

• NONE

OUPUT

• UNKNOWN

getpassword

INPUT

• NAME or UID

OUPUT

• TABLE- values from /etc/passwd

uid,name,gid,password,gecos,dir,shell

bar = require "posix"
bobo = bar.getpasswd("root")
for a,b in pairs(bobo) do print(a,b) end
--uid 0
--name root
--gid 0
--passwd x
--gecos root
--dir /root/
--shell /bin/bash

getprocessid

INPUT

• Selector - either [egid,euid,gid,uid,pgrp,pid,ppid,NULL]

OUPUT

• Number that matches the current process and the selector

bar = require "posix"
print(bar.getprocessid("gid"))
18456 
--it just printed the current process id for the script or interactive lua.

Is there a version difference here? AL 1.7.7 calls this "getpid" Nangel

kill

INPUT

• PID- process identifier
• Signal- to send to the process

OUPUT

bar = require "posix"
--kill your current process
bobo = bar.getprocessid("pid")
bar.kill(bobo,9)
---Signals looks to be the number signals accepted in Unix

link

Hard Links INPUT

• Oldpath-
• Newpath-

'OUTPUT If you want output 0 sucess, nil errors

bar = require "posix"
bobo = bar.link("/etc/passwd", "testfile")
-- 0 for success, nil for errors

mkdir

INPUT

• PATH-path to new dir

OUTPUT If you are looking for output-

• 0 for success
• nil for failure

bar = require "posix"
bar.mkdir("/home/user/bobo")
--set the above to a variable to get output

mkfifo

INPUT

• PATH- where to make the fifo

wait

---

If you are using this under linux also get