I have a lua REPL, and would like to run a lua script file stored as plain text at HTTPS://URL. I understand os.execute() can run OS commands so we can use curl etc. to grab the script then load(). Is that something possible to do in lua REPL with a single line?
Note: If you're going to run source code directly from the web, use https at least, to avoid easy MitM attacks.
To give this question an answer, since Egor will probably not post it as such:
(loadstring or load)(io.popen("wget -qO- https://i.imgur.com/91HtaFp.gif"):read"*a")()
For why this prints Hello world:
loadstring or load is to be compatible with different Lua versions, as the functions loadstring and load were merged at some point (5.2 I believe). io.popen executes its first argument in the shell and returns a file pointer to its stdout.
The "gif" from Egor is not really a GIF (open this in your browser: view-source:https://i.imgur.com/91HtaFp.gif) but a plain text file that contains this text:
GIF89a=GIF89a
print'Hello world'
Basically a GIF starts with GIF89a and the =GIF89a afterwards is just to produce valid Lua, meaning you don't have to use imgur or gifs, you can just as well use raw gists or github.
Now, it's rather unlikely that os.execute is available in a sandbox when io.popen is not, but if it is, you can achieve a one-liner (though drastically longer) using os.execute and temporary files
Lets first write this out because in a single line it will be a bit complex:
(function(u,f)
-- get a temp file name, Windows prefixes those with a \, so remove that
f=f or os.tmpname():gsub('^\\','')
-- run curl, make it output into our temp file
os.execute(('curl -s "%s" -o "%s"'):format(u,f))
-- load/run temp file
loadfile(f)()
os.remove(f)
end)("https://i.imgur.com/91HtaFp.gif");
And you can easily condense that into a single line by removing comments, tabs and newlines:
(function(u,f)f=f or os.tmpname():gsub('^\\','')os.execute(('curl -s "%s" -o "%s"'):format(u,f))loadfile(f)()os.remove(f)end)("https://i.imgur.com/91HtaFp.gif");
Related
I have just started learning the Forth programming language.
I'm using Gforth on Ubuntu. In Gforth interactive console, I want to do indentation but it requires changing line. Enter key didn't work, it executed code. For comparison, for example, when one tests JavaScript code in web browser console, shift+enter change line without executing code. I want something like that. What key should I press? Is there a way other than using text editors like vim?
Best.
Gforth doesn't support multiline editing (see the manual).
A workaround is to edit a file in your favorite editor in another window and reload this file in Gforth console as:
include /tmp/scratch.fs
An external file can be also edited in Gforth console via a command like:
"vim /tmp/scratch.fs" system
So a one-liner for that is:
"vim /tmp/scratch.fs" system "/tmp/scratch.fs" included
That can be wrapped into a definition as:
: scratch "vim /tmp/scratch.fs" system "/tmp/scratch.fs" included ;
So the word scratch will open an editor and than load the edited file.
NB: if you use a quite old build of Gforth, you have to use s" ccc" instead of "ccc" for string literals.
To conditionally include/exclude some parts in a file the words [defined] and [if] can be used; to erase the previous instance of the loaded definitions the word marker can be used as:
[defined] _clear [if] _clear [then]
marker _clear
\ some definitions
\ ...
Take into account that usual control-flow words can be used in definitions only.
I've been wondering, if there is an environment variable to set the search path for #use and #load for the ocaml toplevel.
What I think I know so far:
I can use findlib instead of "raw" #use and #load. findlib looks at some environment variables for the search path.
I can set a search path with -I.
Experiments seem to indicate that CAML_LD_LIBRARY_PATH does not influence #use (script loading) and #load (byte code file loading).
(updated) I can use #directory to add the desired path - but unfortunately this only takes a string literal, so i can't pass something I read from the environment at run time. (Update: I forgot to mention #directory originally and why it doesn't fit my use case).
What I want to do:
Run ocaml programs as scripts
Point ocaml to script libraries and script fragments with an environment variable
Avoid, in some scenarios, to create a full findlib library.
Presently I'm not using ocaml as interpreter, but a wrapper that adds a path to the invocation. I want to avoid the wrapper.
(I hope the questions makes sense now, after you know my use case)
So: Is there an environment variable to set the search path for #use and #load without resorting to a wrapper?
More Details
What I'm currently doing:
#!/usr/bin/env oscript2
#use "MyScript"
#load "SomeModule.cmo"
(* ... more ocaml *)
oscript2 is a wrapper around ocaml that basically sets the search paths for #use and #load, but finally executes the toplevel ocaml withe something like
exec ocaml -I .... ...some-byte-code-modules... "$#"
MyScript and SomeModule.cmo live outside of the "normal" Ocaml search path. The actual location might change, but after login (and working through the profie scripts) there is an environment variable (today it's OSCRIPTLOAD_PATH) that tells me, where alle loadable byte code and ocaml script files might live.
This works well, a variant of that setup has been in use for years (at least 7).
The one thing that bothers me there, is: The wrapper, the simple fact of it's presence, looks homebrew, so I'd like to avoid it, to make a better impression on potential future users of the script collection. What I'd like to do
#!/usr/bin/env ocaml
#use "MyScript"
#load "SomeModule.cmo"
(* ... more ocaml *)
and have ocaml itself pick up the search path from some environment variable (I'm free to change the variable name, that is under my control, but I don't want to install script and byte code libs into the default search path, and, as already stated, I' asking if I can do that without findlib).
Basically (as already stated at the very beginning) I'm looking for an environment variable that controls the search path for #use and #load. I'm not looking for toplevel directives and not for wrappers that retrofit this feature. (Thanks everyone for those suggestions, but unfortunately I've already gone that road, it's feasible, but here I'm looking for an alternative purely for cosmetic reasons).
Recent research didn't bring up that such a variable exists, but I thought I'd be asking here, before giving up on it.
From inside the OCaml toplevel you can use the #directory "foo";; primitive to add an include directory.
Here's a shell script that runs the OCaml toplevel while adding a directory to the search path taken from an environment variable named EXTRA_OCAML_DIR.
#!/bin/sh
ocaml -I "$EXTRA_OCAML_DIR" "$#"
If you run this instead of ocaml, you will have a directory in the load path specified by an environment variable.
It seems a little obvious, but maybe it will spark an idea that is more helpful.
How can I get the output of ls? I want to add a indirection operator =>, and it's function is same as >, it means in the command line $ls => Files, the list of files in the directory is stored in the file Files
Output redirection (and all other redirection for that matter) is a facility provided by the shell, not by the ls program. The ls just writes its output to standard output and, if the shell has redirected that to a file, that's where it goes.
So, if you want to add a => token, it's the shell that you're going to have to modify, recompile and install. That's not necessarily an easy task, I've made changes to bash in the past and, while it's relatively easy to tinker around the edges (I added an internal command for outputting the PS1 result string), I suspect redirection may be a little more difficult.
Still, it may be a matter of simply creating a new token => and copying the code that's currently executed for >. It may also be that ash, the Minix3 shell, is a lot cleaner than bash. My advice would be to investigate ash, specifically the version found in Minix3, and just have a play.
I'm trying to run an executable using Lua's os.execute() function. If I do something like the following it does not work:
os.execute("C:\\\Program Files\\\Movie Maker\\\moviemk.exe")
However, if I put my lua file in the same path that moviemk.exe is in then it can call it.
Any ideas why this may be?
P.S. I'm using Windows XP SP3
This is a classic problem with the command shell. It isn't really a Windows specific problem, except that on *nix, people never really got into the habit of putting spaces in file names, and Windows puts spaces in several default system places such as C:\Program Files.
What is happening is that os.execute(str) is implemented in terms of the ANSI C function system(str), which on Windows tries to duplicate the effect of typing "cmd /C "..str to the command prompt. (On *nix, it uses /bin/sh -c instead of cmd /C.)
The classic problem is that this has to split the complete command string at whitespace to decide what program to run, and what its arguments are.
Your original example: os.execute("C:\\Program Files\\Movie Maker\\moviemk.exe") effectively became cmd /c c:\program files\movie maker\moviemk.exe, which after splitting it up on whitespace, CMD tried to find a program named c:\program to execute with arguments named files\movie and maker\moviemk.exe. This isn't what you intended.
The solution is to be much more defensive about quoting.
I would write this as:
os.execute [["C:\Program Files\Movie Maker\Moviemk.exe"]]
If there were additional command line arguments to be supplied, I would use double-quotes around each, and a single space between arguments. Using the long string syntax [[...]] has the advantage that backslash isn't a special character, so you don't need extra leaning toothpicks making it harder to read the string literal.
Using double quotes around each argument should work on both Windows and *nix, although it is harder to find commands that are the same on both platforms, of course.
One other detail to be aware of is that \Programs Files might not be on C:. There might not even be a disk named C:. (My work PC boots from E: and I find more buggy programs that way.) The easiest way to learn the correct pathname is to just use the environment variable ProgramFiles. There are many other ways.
Try:
os.execute("C:\\Program Files\\Movie Maker\\moviemk.exe")
or:
os.execute("C:/Program Files/Movie Maker/moviemk.exe")
The '\' character is used for escape characters in Lua.
Is there a way to run a file through a print driver without opening the application?
Ex: run a .docx file, without opening word, and save it to file?
Since it is a .docx-file Microsoft Word is probably the best program to do the task.
I would have a look at the [command line arguments] to Word:
Have a look at the following switches:
/q, /n, /mFilePrintDefault and /mFileExit
(/q and /n explained in the page above, and /mXxxx refers to macros. Have a look att google.)
Example:
WINWORD.EXE your_document.docx /mFilePrintDefault /mFileExit /q /n
The following page seems to explain how to convert it to PDF.
What you are looking for is called "headless start" of the program which needs to print.
I know for sure that OpenOffice can do this.
Basically, you need to start it and invoke a macro which will do the printing. Even more, you can print to a PDF, HTML, or anything else that Oo supports.
This negates the need for install of Microsoft Word and the cost of license, because OpenOffice is free.
If you are looking only for .docx silent printing then [aioobe] answer is the best. If you want a more generic silent print program that runs on Windows, use powershell or .NET and use the print verb. http://www.eggheadcafe.com/software/aspnet/30441939/how-to-suppress-printdialog-when-using-print-verb.aspx provides an example.
Hope this helps, if so +1 please :)
You might be interested in DocTo which will convert a word document to another file format, including pdf and XPS but does require Word on the machine.
For example
Docto -f "c:\docs\mydocument.docx" -o "c:\output" -t wdFormatPDF
Will output mydocument.docx to c:\output\mydocument.pdf as a pdf file.