Re: getting the path to the executing program
Hal Daume III [EMAIL PROTECTED] writes: If I may suggest, a Haskell implementation may want to give a programmer a way to obtain the unmangled argv0. If I may second that, ... You mean like nhc98 and hbc have always done...? Regards, Malcolm ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
Hal Daume wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? basically, i want to be able to read a file which i know will be in the same directory as the current program, but not necessarily in the same directory that we're running it from. Actually, if you want to read a file located in the same directory as the executable itself, you don't need the absolute path of the executable. You merely need any path to the executable that is valid with respect to the working directory at the start-up time. Some four years ago I wrote a similar code that seems to work reliably across HP/UX, Solaris, Linux, FreeBSD and various versions of Winxx (from Windows98 onwards). The application has been deployed in more than thousand copies and nobody has complained regarding the path. The application reliably finds the name of a file from the application's own directory no matter how the application was invoked: from its own directory by name, from its own directory as ./appname, from its own directory by the absolute or relative (../dir/appname) name, or from some other directory by the absolute or relative name, or by a symbolic link. The only assumption is that neither forward nor backward slash can appear in a file path. The latter assumption seems to always hold on Winxx, which takes the forward slash as a path delimiter too. On Unixen, the backward slash in file names seems to appear only on hacked systems. So, the failure of the approach in that case should be considered a feature. The algorithm is simple: remove the last path-component from argv[0] and append the local file name to the result (which may be an empty string). A path component is a sequence of characters that does not contain a path delimiter. Note that argv[0] may not end in a path delimiter. The algorithm requires argv[0] as it is given by the OS. Alas, neither GHC nor Hugs seem to give us that. Therefore, I'm inclosing the Scheme code that implements the algorithm. I do not have the guts to post the original code (which was in Perl). If I may suggest, a Haskell implementation may want to give a programmer a way to obtain the unmangled argv0. ; last-delimiter STR - POS ; where POS is the location of the last path-delimiter in STR ; or #f (define delimiters '(#\\ #\/)) (define (last-delimiter str) (let loop ((i (- (string-length str) 1))) (cond ((negative? i) #f) ((memv (string-ref str i) delimiters) i) (else (loop (- i 1)) (define local-file-name that-is-it) ; Like with-input-from file, but the file ; is assumed to be in the same directory as the executable ; itself (define (with-input-from-local-file local-file-name thunk) (let* ((argv0 (car (command-line))) (last-delim (last-delimiter argv0))) (with-input-from-file (if last-delim (if ( (+ 1 last-delim) (string-length argv0)) (string-append (substring argv0 0 (+ 1 last-delim)) local-file-name) (error 'with-input-from-local-file path-delim at the end of argv0: argv0)) local-file-name) thunk))) (display (with-input-from-local-file local-file-name read)) (newline) ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
Hi, If I may suggest, a Haskell implementation may want to give a programmer a way to obtain the unmangled argv0. If I may second that, ... -- Hal Daume III | [EMAIL PROTECTED] Arrest this man, he talks in maths. | www.isi.edu/~hdaume ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
[EMAIL PROTECTED] wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? basically, i want to be able to read a file which i know will be in the same directory as the current program, but not necessarily in the same directory that we're running it from. Actually, if you want to read a file located in the same directory as the executable itself, you don't need the absolute path of the executable. You merely need any path to the executable that is valid with respect to the working directory at the start-up time. Some four years ago I wrote a similar code that seems to work reliably across HP/UX, Solaris, Linux, FreeBSD and various versions of Winxx (from Windows98 onwards). The application has been deployed in more than thousand copies and nobody has complained regarding the path. The application reliably finds the name of a file from the application's own directory no matter how the application was invoked: from its own directory by name, from its own directory as ./appname, from its own directory by the absolute or relative (../dir/appname) name, or from some other directory by the absolute or relative name, or by a symbolic link. You omitted the most important case: from an arbitrary directory via a simple filename, looked up via $PATH. For that case, you need to iterate through the components of $PATH until you find one which contains a suitably-named file which has execute permission for the current user. That still doesn't handle the pathological cases, e.g. where the filesystem has been changed such that the original command would no longer refer to the same executable, or where argv[0] doesn't contain the filename used, but it's likely to be close enough for the cases where someone isn't deliberately trying to make it fail. -- Glynn Clements [EMAIL PROTECTED] ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
Sadly, this doesn't seem to work:
9:26am albini:SVMseq/ cat Foo.hs
module Main where
import System.Environment
main = getEnv _ = putStrLn
9:27am albini:SVMseq/ ghc Foo.hs -o foo
9:27am albini:SVMseq/ ./foo
Fail: does not exist
Action: getEnv
Reason: no environment variable
File: _
On Thu, 8 Jan 2004, Christopher Milton wrote:
The environmental var _ in $ENV{_} (pardon my Perlish) holds
the full path name of the command currently executing (itself), at
least on RedHat Linux and HP-UX, so you should be able to use
getEnv... I think...
--- Hal Daume III [EMAIL PROTECTED] wrote:
is there a function, related to getProgName, which returns the (absolute)
path to the current program?
basically, i want to be able to read a file which i know will be in the
same directory as the current program, but not necessarily in the same
directory that we're running it from.
=
Christopher Milton
[EMAIL PROTECTED]
--
Hal Daume III | [EMAIL PROTECTED]
Arrest this man, he talks in maths. | www.isi.edu/~hdaume
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Re: getting the path to the executing program
On Thu, Jan 08, 2004 at 09:06:44AM -0800, Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? A non-portable Linux solution: System.Posix.readSymbolicLink /proc/self/exe Best regards, Tom -- .signature: Too many levels of symbolic links ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
On Thursday 08 January 2004 18.06, Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? basically, i want to be able to read a file which i know will be in the same directory as the current program, but not necessarily in the same directory that we're running it from. I don't know how to do this in a portable way, but on unix/linux you can use the standard trick of reading the symbolic link /proc/process-id/exe . For example: import System.Posix.Files (readSymbolicLink) import System.Posix.Process (getProcessID) main = do pid - getProcessID path - readSymbolicLink (/proc/ ++ (show pid) ++ /exe) putStrLn (Absolute path of this program is ++ path) PS. This doesn't work with interpreted code (Hugs, GHCi) in which case you get the path to the interpreter itself. Cheers Per ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
On Thu, Jan 08, 2004 at 07:02:04PM +0100, Tomasz Zielonka wrote: On Thu, Jan 08, 2004 at 09:06:44AM -0800, Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? A non-portable Linux solution: System.Posix.readSymbolicLink /proc/self/exe A non-portable FreeBSD solution: System.Posix.readSymbolicLink /proc/curproc/file Best regards, Tom -- .signature: Too many levels of symbolic links ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? Well, the absolute path name is not necessarily unique, nor is it guaranteed to exist. :) -- Lennart ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
True. Replace the with a and ? with , if it exists?. On Thu, 8 Jan 2004, Lennart Augustsson wrote: Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? Well, the absolute path name is not necessarily unique, nor is it guaranteed to exist. :) -- Lennart ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell -- Hal Daume III | [EMAIL PROTECTED] Arrest this man, he talks in maths. | www.isi.edu/~hdaume ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: getting the path to the executing program
Hal Daume III [EMAIL PROTECTED] writes: True. Replace the with a and ? with , if it exists?. On Thu, 8 Jan 2004, Lennart Augustsson wrote: Hal Daume III wrote: is there a function, related to getProgName, which returns the (absolute) path to the current program? Well, the absolute path name is not necessarily unique, nor is it guaranteed to exist. :) http://groups.google.com/groups?hl=enlr=ie=UTF-8oe=utf-8threadm=9201%40june.cs.washington.edurnum=1prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3Dutf-8%26selm%3D9201%2540june.cs.washington.edu This is all you can get, I am afraid. Feri. ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
