Is it possible to save the directory info obtained from os.execute("dir") into a string form?
So in the directory <DELL> I have the files info.txt and readme.txt. I want to use os.execute("dir") and have the files info.txt and readme.txt saved into string DIR. So I guess the entire string would read something like DELL; info.txt, readme.txt.
No, but using io.popen should work.
io.popen (prog [, mode])
This function is system dependent and is not available on all platforms.
Starts program prog in a separated process and returns a file handle that you can use to read data from this program (if mode is "r", the default) or to write data to this program (if mode is "w").
local p = io.popen( "dir", "r" )
local output = p:read "*a"
p:close( )
-- and use output
Related
I'm using Lua in Scite on Windows, but hopefully this is a general Lua question.
Let's say I want to write a temporary string content to a temporary file in Lua - which I want to be eventually read by another program, - and I tried using io.tmpfile():
mytmpfile = assert( io.tmpfile() )
mytmpfile:write( MYTMPTEXT )
mytmpfile:seek("set", 0) -- back to start
print("mytmpfile" .. mytmpfile .. "<<<")
mytmpfile:close()
I like io.tmpfile() because it is noted in https://www.lua.org/pil/21.3.html :
The tmpfile function returns a handle for a temporary file, open in read/write mode. That file is automatically removed (deleted) when your program ends.
However, when I try to print mytmpfile, I get:
C:\Users\ME/sciteLuaFunctions.lua:956: attempt to concatenate a FILE* value (global 'mytmpfile')
>Lua: error occurred while processing command
I got the explanation for that here Re: path for io.tmpfile() ?:
how do I get the path used to generate the temp file created by io.tmpfile()
You can't. The whole point of tmpfile is to give you a file handle without
giving you the file name to avoid race conditions.
And indeed, on some OSes, the file has no name.
So, it will not be possible for me to use the filename of the tmpfile in a command line that should be ran by the OS, as in:
f = io.popen("python myprog.py " .. mytmpfile)
So my questions are:
Would it be somehow possible to specify this tmpfile file handle as the input argument for the externally ran program/script, say in io.popen - instead of using the (non-existing) tmpfile filename?
If above is not possible, what is the next best option (in terms of not having to maintain it, i.e. not having to remember to delete the file) for opening a temporary file in Lua?
You can get a temp filename with os.tmpname.
local n = os.tmpname()
local f = io.open(n, 'w+b')
f:write(....)
f:close()
os.remove(n)
If your purpose is sending some data to a python script, you can also use 'w' mode in popen.
--lua
local f = io.popen(prog, 'w')
f:write(....)
#python
import sys
data = sys.stdin.readline()
I need a list of directory in LUA
Suppose I have a directory path as "C:\Program Files"
I need a list of all the folders in that particular path and how to search any particular folder in that list.
Example
Need a list of all the folder in path "C:\Program Files"
Below are folder name in the above path
test123
test4567
folder 123
folder 456
folder 456 789
Need to get the above in a list and then have to search for a particular string like folder 456 in folder 456 789 only.
Have Tried below code. Something I am missing below:-
local function Loc_Lines( str )
--
local ret= {} -- 0 lines
while str do
local _,_,line,tail= string.find( str, "(.-)\n(.+)" )
table.insert( ret, line or str )
str= tail
Print (str)
end
return ret
end
local function Loc_ShellCommand( cmd )
--
local str= nil
--
local f= io.popen( cmd ) -- no command still returns a handle :(
if f then
str= f:read'*a'
Print(str)
f:close()
end
if str=="" then -- take no output as a failure (we can't tell..)
Print("hi")
str= nil
end
-- Remove terminating linefeed, if any (eases up one-line analysis)
--
if str then
if string.sub( str, -1 ) == '\n' then
str= string.sub( str, 1, -2 )
end
end
return str
end
local function Loc_DirCmd( cmd )
Print(cmd)
local str= Loc_ShellCommand( cmd )
return Loc_Lines(str)
end
local function Loc_DirList( dirname )
local ret= {}
local lookup= {}
local tbl= Loc_DirCmd( "dir /AD /B "..dirname ) -- only dirs
-- Add slash to every dir line
--
for i,v in ipairs(tbl) do
table.insert( ret, v..'\\' )
lookup[v]= true
end
-- Return with forward slashes
--
if true then
for i=1,table.getn(ret) do
ret[i]= string.gsub( ret[i], '\\', '/' )
Print (ret[i])
end
end
return ret
end
Loc_DirList("C:\\Program Files\\")
I hate having to install libraries (especially those that want me to use installer packages to install them). If you're looking for a clean solution for a directory listing on an absolute path in Lua, look no further.
Building on the answer that sylvanaar provided, I created a function that returns an array of all the files for a given directory (absolute path required). This is my preferred implementation, as it works on all my machines.
-- Lua implementation of PHP scandir function
function scandir(directory)
local i, t, popen = 0, {}, io.popen
local pfile = popen('ls -a "'..directory..'"')
for filename in pfile:lines() do
i = i + 1
t[i] = filename
end
pfile:close()
return t
end
If you are using Windows, you'll need to have a bash client installed so that the 'ls' command will work - alternately, you can use the dir command that sylvanaar provided:
'dir "'..directory..'" /b /ad'
Take the easy way, install lfs. Then use the following constructs to find what you need:
require'lfs'
for file in lfs.dir[[C:\Program Files]] do
if lfs.attributes(file,"mode") == "file" then print("found file, "..file)
elseif lfs.attributes(file,"mode")== "directory" then print("found dir, "..file," containing:")
for l in lfs.dir("C:\\Program Files\\"..file) do
print("",l)
end
end
end
notice that a backslash equals [[\]] equals "\\", and that in windows / is also allowed if not used on the cmd itself (correct me if I'm wrong on this one).
for dir in io.popen([[dir "C:\Program Files\" /b /ad]]):lines() do print(dir) end
*For Windows
Outputs:
Adobe
Bitcasa
Bonjour
Business Objects
Common Files
DVD Maker
IIS
Internet Explorer
iPod
iTunes
Java
Microsoft Device Emulator
Microsoft Help Viewer
Microsoft IntelliPoint
Microsoft IntelliType Pro
Microsoft Office
Microsoft SDKs
Microsoft Security Client
Microsoft SQL Server
Microsoft SQL Server Compact Edition
Microsoft Sync Framework
Microsoft Synchronization Services
Microsoft Visual Studio 10.0
Microsoft Visual Studio 9.0
Microsoft.NET
MSBuild
...
Each time through the loop you are given a new folder name. I chose to print it as an example.
I don't like installing libraries either and am working on an embedded device with less memory power then a pc. I found out that using 'ls' command lead to an out of memory. So I created a function that uses 'find' to solve the problem.
This way it was possible to keep memory usage steady and loop all the 30k files.
function dirLookup(dir)
local p = io.popen('find "'..dir..'" -type f') --Open directory look for files, save data in p. By giving '-type f' as parameter, it returns all files.
for file in p:lines() do --Loop through all files
print(file)
end
end
IIRC, getting the directory listing isn't possible with stock Lua. You need to write some glue code yourself, or use LuaFileSystem. The latter is most likely the path of least resistance for you. A quick scan of the docs shows lfs.dir() which will provide you with an iterator you can use to get the directories you are looking for. At that point, you can then do your string comparison to get the specific directories you need.
You also install and use the 'paths' module. Then you can easily do this as follow:
require 'paths'
currentPath = paths.cwd() -- Current working directory
folderNames = {}
for folderName in paths.files(currentPath) do
if folderName:find('$') then
table.insert(folderNames, paths.concat(currentPath, folderName))
end
end
print (folderNames)
-- This will print all folder names
Optionally, you can also look for file names with a specific extension by replacing fileName:find('$') with fileName:find('txt' .. '$')
If you're running on a Unix-based machine you can get a numerically-sorted list of files using the following code:
thePath = '/home/Your_Directory'
local handle = assert(io.popen('ls -1v ' .. thePath))
local allFileNames = string.split(assert(handle:read('*a')), '\n')
print (allFileNames[1]) -- This will print the first file name
The second code also excludes files such as '.' and '..'. So it's good to go!
Don't parse ls, it's evil! Use find with zero-terminated strings instead (on linux):
function scandir(directory)
local i, t = 0, {}
local pfile = assert(io.popen(("find '%s' -maxdepth 1 -print0"):format(directory), 'r'))
local list = pfile:read('*a')
pfile:close()
for filename in s:gmatch('[^\0]+')
i = i + 1
t[i] = filename
end
return t
end
WARNING: however, as an acceped answer this apporach could be exploited if directory name contain ' in it. Only one safe solution is to use lfs or other special library.
Few fixes of val says Reinstate Monica solution:
function scandir(directory)
local pfile = assert(io.popen(("find '%s' -mindepth 1 -maxdepth 1 -type d -printf '%%f\\0'"):format(directory), 'r'))
local list = pfile:read('*a')
pfile:close()
local folders = {}
for filename in string.gmatch(list, '[^%z]+') do
table.insert(folders, filename)
end
return folders
end
Now it filters by folders, excludes dir itself and prints only names.
I am constructing a general purpose function to read a text file, which may be Ascii, UTF-8 or UTF-16. (The encoding is known when the function is invoked). The file name may contain UTF8 characters, so the standard lua io functions are not a solution. I have no control over the Lua implementation (5.3) or the binary modules available in the environment.
My current code is:
require "luacom"
local function readTextFile(sPath, bUnicode, iBits)
local fso = luacom.CreateObject("Scripting.FileSystemObject")
if not fso:FileExists(sPath) then return false, "" end --check the file exists
local so = luacom.CreateObject("ADODB.Stream")
--so.CharSet defaults to Unicode aka utf-16
--so.Type defaults to text
so.Mode = 1 --adModeRead
if not bUnicode then
so.CharSet = "ascii"
elseif iBits == 8 then
so.CharSet = "utf-8"
end
so:Open()
so:LoadFromFile(sPath)
local contents = so:ReadText()
so:Close()
return true, contents
end
--test Unicode(utf-16) files
local file = "D:\\OneDrive\\Desktop\\utf16.txt" --this exists
local booOK, factsetcontents = readTextFile(file, true, 16)
When executed I get the error: COM exception:(d:\my\lua\luacom-master\src\library\tluacom.cpp,382):Operation is not allowed in this context on line 19 [local stream = so:LoadFromFile(sPath)]
I've pored over the ADO documentation and am obviously missing something that is staring me in the face! Is what I'm trying to do impossible?
ETA: If I comment out the line so.Mode = 1, this works. Which is great, but I don't understand why, which meaans I may end up making the same mistake unwittingly, whatever that mistake is!
I don't know about AdoDB Stream.Mode and why the function failed. But I think it's rather tricky to use a ADODB COM object on Windows to read ASCII/UTF8/UNICODE encoded files.
You can instead :
use standard Lua io.open function in binary mode and use manual decoding of the bytes content
use a binary module to do all the work
use a specific Lua implementation for Windows that can read/write those kind of encoded files natively, like LuaRT
I am learning the Lua IO library. I'm having trouble with io.write(). In Programming Design in Lua, there is a piece of code that iterates through the file line by line and precedes each line with a serial number.
This is the file I`m working on:
test file: "iotest.txt"
This is my code
io.input("iotest.txt")
-- io.output("iotest.txt")
local count = 0
for line in io.lines() do
count=count+1
io.write(string.format("%6d ",count), line, "\n")
end
This is the result of the terminal display, but this result cannot be written to the file, whether I add IO. Output (" iotest.txt ") or not.
the results in terminal
This is the result of file, we can see there is no change
The result after code running
Just add io.flush() after your write operations to save the data to the file.
io.input("iotest.txt")
io.output("iotestout.txt")
local count = 0
for line in io.lines() do
count=count+1
io.write(string.format("%6d ",count), line, "\n")
end
io.flush()
io.close()
Refer to Lua 5.4 Reference Manual : 6.8 - Input and Output Facilities
io.flush() will save any written data to the output file which you set with io.output
See koyaanisqatsi's answer for the optional use of file handles. This becomes especially useful if you're working on multiple files at a time and gives you more control on how to interact with the file.
That said you should also have different files for input and output. You'll agree that it doesn't make sense to read and write from and to the same file alternatingly.
For writing to a file you need a file handle.
This handle comes from: io.open()
See: https://www.lua.org/manual/5.4/manual.html#6.8
A file handle has methods that acts on self.
Thats the function after the : at file handle.
So io.write() puts out on stdout and file:write() in a file.
Example function that can dump a defined function to a file...
fdump=function(func,path)
assert(type(func)=="function")
assert(type(path)=="string")
-- Get the file handle (file)
local file,err = io.open(path, "wb")
assert(file, err)
local chunk = string.dump(func,true)
file:write(chunk)
file:flush()
file:close()
return 'DONE'
end
Here are the methods, taken from io.stdin
close = function: 0x566032b0
seek = function: 0x566045f0
flush = function: 0x56603d10
setvbuf = function: 0x56604240
write = function: 0x56603e70
lines = function: 0x566040c0
read = function: 0x56603c90
This makes it able to use it directly like...
( Lua console: lua -i )
> do io.stdout:write('Input: ') local result=io.stdin:read() return result end
Input: d
d
You are trying to open the same file for reading and writing at the same time. You cannot do that.
There are two possible solutions:
Read from file X, iterate through it and write the result to another file Y.
Read the complete file X into memory, close file X, then delete file X, open the same filename for writing and write to it while iterating through the original file (in memory).
Otherwise, your approach is correct although file operations in Lua are more often done using io.open() and file handles instead of io.write() and io.read().
I need a list of directory in LUA
Suppose I have a directory path as "C:\Program Files"
I need a list of all the folders in that particular path and how to search any particular folder in that list.
Example
Need a list of all the folder in path "C:\Program Files"
Below are folder name in the above path
test123
test4567
folder 123
folder 456
folder 456 789
Need to get the above in a list and then have to search for a particular string like folder 456 in folder 456 789 only.
Have Tried below code. Something I am missing below:-
local function Loc_Lines( str )
--
local ret= {} -- 0 lines
while str do
local _,_,line,tail= string.find( str, "(.-)\n(.+)" )
table.insert( ret, line or str )
str= tail
Print (str)
end
return ret
end
local function Loc_ShellCommand( cmd )
--
local str= nil
--
local f= io.popen( cmd ) -- no command still returns a handle :(
if f then
str= f:read'*a'
Print(str)
f:close()
end
if str=="" then -- take no output as a failure (we can't tell..)
Print("hi")
str= nil
end
-- Remove terminating linefeed, if any (eases up one-line analysis)
--
if str then
if string.sub( str, -1 ) == '\n' then
str= string.sub( str, 1, -2 )
end
end
return str
end
local function Loc_DirCmd( cmd )
Print(cmd)
local str= Loc_ShellCommand( cmd )
return Loc_Lines(str)
end
local function Loc_DirList( dirname )
local ret= {}
local lookup= {}
local tbl= Loc_DirCmd( "dir /AD /B "..dirname ) -- only dirs
-- Add slash to every dir line
--
for i,v in ipairs(tbl) do
table.insert( ret, v..'\\' )
lookup[v]= true
end
-- Return with forward slashes
--
if true then
for i=1,table.getn(ret) do
ret[i]= string.gsub( ret[i], '\\', '/' )
Print (ret[i])
end
end
return ret
end
Loc_DirList("C:\\Program Files\\")
I hate having to install libraries (especially those that want me to use installer packages to install them). If you're looking for a clean solution for a directory listing on an absolute path in Lua, look no further.
Building on the answer that sylvanaar provided, I created a function that returns an array of all the files for a given directory (absolute path required). This is my preferred implementation, as it works on all my machines.
-- Lua implementation of PHP scandir function
function scandir(directory)
local i, t, popen = 0, {}, io.popen
local pfile = popen('ls -a "'..directory..'"')
for filename in pfile:lines() do
i = i + 1
t[i] = filename
end
pfile:close()
return t
end
If you are using Windows, you'll need to have a bash client installed so that the 'ls' command will work - alternately, you can use the dir command that sylvanaar provided:
'dir "'..directory..'" /b /ad'
Take the easy way, install lfs. Then use the following constructs to find what you need:
require'lfs'
for file in lfs.dir[[C:\Program Files]] do
if lfs.attributes(file,"mode") == "file" then print("found file, "..file)
elseif lfs.attributes(file,"mode")== "directory" then print("found dir, "..file," containing:")
for l in lfs.dir("C:\\Program Files\\"..file) do
print("",l)
end
end
end
notice that a backslash equals [[\]] equals "\\", and that in windows / is also allowed if not used on the cmd itself (correct me if I'm wrong on this one).
for dir in io.popen([[dir "C:\Program Files\" /b /ad]]):lines() do print(dir) end
*For Windows
Outputs:
Adobe
Bitcasa
Bonjour
Business Objects
Common Files
DVD Maker
IIS
Internet Explorer
iPod
iTunes
Java
Microsoft Device Emulator
Microsoft Help Viewer
Microsoft IntelliPoint
Microsoft IntelliType Pro
Microsoft Office
Microsoft SDKs
Microsoft Security Client
Microsoft SQL Server
Microsoft SQL Server Compact Edition
Microsoft Sync Framework
Microsoft Synchronization Services
Microsoft Visual Studio 10.0
Microsoft Visual Studio 9.0
Microsoft.NET
MSBuild
...
Each time through the loop you are given a new folder name. I chose to print it as an example.
I don't like installing libraries either and am working on an embedded device with less memory power then a pc. I found out that using 'ls' command lead to an out of memory. So I created a function that uses 'find' to solve the problem.
This way it was possible to keep memory usage steady and loop all the 30k files.
function dirLookup(dir)
local p = io.popen('find "'..dir..'" -type f') --Open directory look for files, save data in p. By giving '-type f' as parameter, it returns all files.
for file in p:lines() do --Loop through all files
print(file)
end
end
IIRC, getting the directory listing isn't possible with stock Lua. You need to write some glue code yourself, or use LuaFileSystem. The latter is most likely the path of least resistance for you. A quick scan of the docs shows lfs.dir() which will provide you with an iterator you can use to get the directories you are looking for. At that point, you can then do your string comparison to get the specific directories you need.
You also install and use the 'paths' module. Then you can easily do this as follow:
require 'paths'
currentPath = paths.cwd() -- Current working directory
folderNames = {}
for folderName in paths.files(currentPath) do
if folderName:find('$') then
table.insert(folderNames, paths.concat(currentPath, folderName))
end
end
print (folderNames)
-- This will print all folder names
Optionally, you can also look for file names with a specific extension by replacing fileName:find('$') with fileName:find('txt' .. '$')
If you're running on a Unix-based machine you can get a numerically-sorted list of files using the following code:
thePath = '/home/Your_Directory'
local handle = assert(io.popen('ls -1v ' .. thePath))
local allFileNames = string.split(assert(handle:read('*a')), '\n')
print (allFileNames[1]) -- This will print the first file name
The second code also excludes files such as '.' and '..'. So it's good to go!
Don't parse ls, it's evil! Use find with zero-terminated strings instead (on linux):
function scandir(directory)
local i, t = 0, {}
local pfile = assert(io.popen(("find '%s' -maxdepth 1 -print0"):format(directory), 'r'))
local list = pfile:read('*a')
pfile:close()
for filename in s:gmatch('[^\0]+')
i = i + 1
t[i] = filename
end
return t
end
WARNING: however, as an acceped answer this apporach could be exploited if directory name contain ' in it. Only one safe solution is to use lfs or other special library.
Few fixes of val says Reinstate Monica solution:
function scandir(directory)
local pfile = assert(io.popen(("find '%s' -mindepth 1 -maxdepth 1 -type d -printf '%%f\\0'"):format(directory), 'r'))
local list = pfile:read('*a')
pfile:close()
local folders = {}
for filename in string.gmatch(list, '[^%z]+') do
table.insert(folders, filename)
end
return folders
end
Now it filters by folders, excludes dir itself and prints only names.