FBB::CerrExtractor(3bobcat)
Executing Child Processes
(libbobcat-dev_4.08.03-x.tar.gz)
2005-2018
NAME
FBB::CerrExtractor - Runs external programs writing standard error
SYNOPSIS
#include <bobcat/cerrextractor>
Linking option: -lbobcat
DESCRIPTION
The FBB::CerrExtractor class offers a basic interface for calling
external programs (so-called 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 CerrExtractor object: information written by the
child process to its standard error stream is extracted or read from
CerrExtractor object. The PATH environment variable is not used when
calling child processes: child process programs must be specified using paths.
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 contents as-is. In addition unquoted
escape-sequences may be specified: those escape sequences are evaluated and
replaced by their intended characters (e.g., \100 is converted to @).
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace FBB.
INHERITS FROM
FBB::Exec (private),
FBB::IFdStreambuf (private),
std::istream
CONSTRUCTOR
- CerrExtractor(size_t bufSize = 100):
A bufSize argument may be specified: it defines the internal
buffer size used by the CerrExtractor's streambuf. By default the
stdandard input and standard output streams are not handled.
- CerrExtractor(Mode mode, size_t bufSize = 100):
The mode argument must be CerrExtractor::CLOSE_STD. It
indicates that the standard input and standard error streams are
redirected to /dev/null: the child processes cannot read their
standard input streams and any standard output generated by child
processes is ignored. A bufSize argument may be specified: it
defines the internal buffer size used by the CinInserter's
streambuf.
MEMBERS
- bool execute(std::string const &cmd):
The argument specifies the command to execute: the command itself must
be specified as a path (the 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 CerrExtractor object.
Once 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.
- int ret() const:
Once execute has returned this member provides the actual exit
code of the child process. Its value equals -1 before the first exectue
call.
PROTECTED MEMBER
- 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.
EXAMPLE
#include <iostream>
#include <bobcat/cerrextractor>
using namespace std;
using namespace FBB;
int main()
{
CerrExtractor extractor;
extractor.execute("/bin/cat driver.cc");
cout << extractor.rdbuf();
cerr << "Returning: " << extractor.ret() << "\n"
"again:\n";
extractor.execute("/bin/cat driver.cc");
cout << extractor.rdbuf();
cerr << "Returning: " << extractor.ret() << '\n';
}
FILES
bobcat/cerrextractor - provides the class interface
SEE ALSO
bobcat(7), cininserter(3bobcat), coutextractor(3bobcat),
execl(3), exec(3bobcat),
fork(3bobcat), process(3bobcat), stdextractor(3bobcat).
BUGS
None reported.
DISTRIBUTION FILES
- bobcat_4.08.03-x.dsc: detached signature;
- bobcat_4.08.03-x.tar.gz: source archive;
- bobcat_4.08.03-x_i386.changes: change log;
- libbobcat1_4.08.03-x_*.deb: debian package holding the
libraries;
- libbobcat1-dev_4.08.03-x_*.deb: debian package holding the
libraries, headers and manual pages;
- http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
COPYRIGHT
This is free software, distributed under the terms of the
GNU General Public License (GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).