FBB::StdExtractor - Runs external programs writing standard error
#include <bobcat/cerrextractor>
Linking option:
-lbobcat
The
FBB::StdExtractor class offers a basic interface for calling external
programs (so-called
child processes) writing their standard output and
error streams. The standard input stream of the child processes are by default
not handled by
StdExtractor objects. The child’s standard output
and standard error streams are read through the
StdExtractor object:
information written by the child process to these streams is extracted or read
from
StdExtractor object. The
PATH environment variable is not
used when calling child processes: child process programs must be specified
using paths.
StdExtractor 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.,
\100 is converted to
@).
FBB
All constructors, members, operators and manipulators, mentioned in this
man-page, are defined in the namespace
FBB.
FBB::Exec (private),
FBB::IFdBuf (private),
std::istream
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StdExtractor(size_t bufSize = 100):
A bufSize argument may be specified: it defines the internal buffer
size used by the StdExtractor’s streambuf. By default the
stdandard input stream is not handled.
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CoutExtractor(Mode mode, size_t bufSize = 100):
The mode argument must be StdExtractor::CLOSE_STD. It
indicates that the standard input stream is redirected to
/dev/null: the child processes cannot read their standard input
streams. A bufSize argument may be specified: it defines the
internal buffer size used by the CinInserter’s streambuf.
Copy and move constructors (and assignment operators) are not available.
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void 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 output and standard error streams may be
extracted from the StdExtractor 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.
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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.
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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.
#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’;
}
bobcat/cerrextractor - provides the class interface
bobcat(7),
cerrextractor(3bobcat),
cininserter(3bobcat),
coutextractor(3bobcat),
execl(3),
exec(3bobcat),
fork(3bobcat),
process(3bobcat).
None reported.
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https://fbb-git.gitlab.io/bobcat/: gitlab project
page;
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bobcat_6.02.02-x.dsc: detached signature;
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bobcat_6.02.02-x.tar.gz: source archive;
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bobcat_6.02.02-x_i386.changes: change log;
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libbobcat1_6.02.02-x_*.deb: debian package
containing the libraries;
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libbobcat1-dev_6.02.02-x_*.deb: debian package
containing the libraries, headers and manual pages;
Bobcat is an acronym of `Brokken’s Own Base Classes And
Templates’.
This is free software, distributed under the terms of the GNU General Public
License (GPL).
Frank B. Brokken (
[email protected]).