includefile(include/header)

COMMENT(manpage, section, releasedate, archive, short name)
manpage(FBB::CerrExtractor)(3bobcat)(_CurYrs_)(libbobcat-dev__CurVers_)
                    (Executing Child Processes)

manpagename(FBB::CerrExtractor)(Runs external programs writing standard error)

manpagesynopsis()
    bf(#include <bobcat/cerrextractor>)nl()
    Linking option: tt(-lbobcat) 

manpagedescription()
    The bf(FBB::CerrExtractor) class offers a basic interface for calling
external programs (so-called em(child processes)) writing their standard error
streams. The standard input and standard output streams of the child processes
are by default not handled by ttCerrExtractor) objects. The child's standard
error is read through the tt(CerrExtractor) object: information written by the
child process to its standard error stream is extracted or read from
tt(CerrExtractor) object. The tt(PATH) environment variable is not used when
calling child processes: child process programs must be specified using paths.

tt(CerrExtractor) objects may repeatedly be used to execute the same or
different child processes. 

Arguments passed to child processes may be surrounded by double or single
quotes. Arguments surrounded by double quotes have their double quotes
removed, while interpreting any escape-sequences that may have been used
within. Arguments surrounded by single quotes have their single quotes
removed, while accepting their content as-is. In addition unquoted
escape-sequences may be specified: those escape sequences are evaluated and
replaced by their intended characters (e.g., tt(\100) is converted to tt(@)).

includefile(include/namespace)

manpagesection(INHERITS FROM)
    bf(FBB::Exec) (private),
    bf(FBB::IFdBuf) (private),
    bf(std::istream)

manpagesection(CONSTRUCTOR)

    itemization(
    itb(CerrExtractor(size_t bufSize = 100))
        A tt(bufSize) argument may be specified: it defines the internal
        buffer size used by the tt(CerrExtractor's) streambuf. By default the
        standard input and standard output streams are not handled.

    itb(CerrExtractor(Mode mode, size_t bufSize = 100))
       The tt(mode) argument must be tt(CerrExtractor::CLOSE_STD). It
        indicates that the standard input and standard error streams are
        redirected to tt(/dev/null): the child processes cannot read their
        standard input streams and any standard output generated by child
        processes is ignored. A tt(bufSize) argument may be specified: it
        defines the internal buffer size used by the tt(CinInserter's)
        streambuf.
    )

    Copy and move constructors (and assignment operators) are not available.

manpagesection(MEMBERS)

    itemization(
    itb(void execute(std::string const &cmd))
       The argument specifies the command to execute: the command itself must
        be specified using an absolute path (the tt(PATH) environment variable
        isn't used).  This member immediately returns, after which information
        written by the child process to its standard error stream may be
        extracted from the tt(CerrExtractor) object.

        Once tt(execute) has returned it can be called again, either using the
        same or another command. 

        Arguments passed to the program to be executed as child process may
        optionally be specified using single or double quotes, as described in
        this man-page's DESCRIPTION section.

    itb(int ret() const)
       Once tt(execute) has returned this member provides the actual exit code
        of the child process. Its value equals -1 before the first tt(exectue)
        call.
    )

manpagesection(PROTECTED MEMBER)

    itemization(
    itb(Pipe &childOutPipe())
       If derived classes need to override the redirections-members then they
        probabaly need access to the pipe written by the child process. This
        member provides a reference to that pipe. By default the parent
        process reads information from the pipe, while the child process
        inserts its standard error output into the pipe.
    )

manpagesection(EXAMPLE)

    verbinclude(../../cerrextractor/driver/driver.cc)

manpagefiles()
    em(bobcat/cerrextractor) - provides the class interface

manpageseealso()
    bf(bobcat)(7), bf(cininserter)(3bobcat), bf(coutextractor)(3bobcat), 
    bf(execl)(3), bf(exec)(3bobcat), 
    bf(fork)(3bobcat), bf(process)(3bobcat), bf(stdextractor)(3bobcat).

manpagebugs()
    None reported.

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