When I am writing my own interpreter... Post: 302141055

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Top Forums Programming When I am writing my own interpreter... Post 302141055 by Legend986 on Wednesday 17th of October 2007 01:25:32 PM

10-17-2007

Registered User

Thank you so much. Can I say that "nano" or "vi" is a process and a command like "ls | grep .c" is a job?

And while implementing pipes, when I issue a command such as "ls | grep .c" in my interpreter, after parsing it, what should I be doing? I read about file descriptors and am assuming the following has to be done:

1. Parse the command line
2. argv[0] contains ls, so fork a process and execute it but redirect the output to a file (I don't know how this can be done internally in the C Code. I know I need to use the execv command to execute but how will I redirect?)
3. In the next parse, I scan the "|" character and so I know that the user wants to pipe the output and at this stage I would fork another process with the argv[2] string i.e. "grep .c" (but this will be stored in argv[2] and argv[3]. How will I know that the second one has command line arguments too and how should I handle them?) and then direct the output of this to the stdout.

Please let me know if the above steps are ok...

Legend986

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LEARN ABOUT DEBIAN

binfmtasm-interpreter

binfmtasm(1)							     binfmt_C							      binfmtasm(1)

NAME

       binfmtasm-interpreter - binfmt_misc Assembly handler

SYNOPSIS

       binfmtasm-interpreter Assembly-source-file-name [command-line opions ...]

DESCRIPTION

       binfmtasm-interpreter compiles an assembly source file specified on the command-line using gas compiler, and executes the resulting file.

       It  is  designed  to be used as a handler for binfmt_misc handler, which is a system used in Linux for handling arbitrary files as executa-
       bles.

       The command-line options are passed on to the compiled binary.

FILE MAGIC

       There is a requirement for C++ source files to have the magic characters /*BINFMTASMCPP: at the beginning of the file.

       That line also is used to specify the additional command-line options for the assmebler.

ENVIRONMENT

       GAS    The compiler used.  The default is to use gcc

       AS     The compiler used, if GAS variable is not set.

	      Will fall back to using GCC and CC

       BINFMTCTMPDIR

	      Temporary directory used for binary and execution.

	      Falls back to $TMPDIR $TEMPDIR or /tmp

       BINFMTC_DEBUG
	      enables debug output if set.

       BINFMTASM_GAS_OPTS
	      Additional G++ options.  Use BINFMTC_DEBUG to verify the options being passed on to g++.

	      The default is  -O2 -Wall

AUTHOR

       Junichi Uekawa (dancer@debian.org)

       Upstream page is available at http://www.netfort.gr.jp/~dancer/software/

SEE ALSO

       binfmtc-interpreter(1), binfmtcxx-interpreter(1), binfmtf-interpreter(1), binfmtf95-interpreter(1), binfmtgcj-interpreter(1)

binfmt_misc Dancer						    2005 May 3							      binfmtasm(1)