diff options
| -rw-r--r-- | process.c | 64 |
1 files changed, 37 insertions, 27 deletions
@@ -2929,44 +2929,44 @@ rb_f_system(int argc, VALUE *argv) * * For example, stderr can be merged into stdout as follows: * - * pid = spawn(command, STDERR=>STDOUT) * pid = spawn(command, :err=>:out) * pid = spawn(command, 2=>1) * pid = spawn(command, STDERR=>:out) + * pid = spawn(command, STDERR=>STDOUT) * * The hash keys specifies a file descriptor * in the child process started by <code>spawn</code>. - * :err, STDERR and 2 specifies the standard error stream. + * :err, 2 and STDERR specifies the standard error stream (stderr). * * The hash values specifies a file descriptor * in the parent process which invokes <code>spawn</code>. - * :out, STDOUT and 1 specifies the standard output stream. + * :out, 1 and STDOUT specifies the standard output stream (stdout). * * In the above example, * the standard output in the child process is not specified. * So it is inherited from the parent process. * - * The standard input stream can be specifed by :in, STDIN and 0. + * The standard input stream (stdin) can be specifed by :in, 0 and STDIN. * * A filename can be specified as a hash value. * - * pid = spawn(command, STDIN=>"/dev/null") # read mode - * pid = spawn(command, STDOUT=>"/dev/null") # write mode - * pid = spawn(command, STDERR=>"log") # write mode + * pid = spawn(command, :in=>"/dev/null") # read mode + * pid = spawn(command, :out=>"/dev/null") # write mode + * pid = spawn(command, :err=>"log") # write mode * pid = spawn(command, 3=>"/dev/null") # read mode * - * For standard output and standard error, + * For stdout and stderr, * it is opened in write mode. * Otherwise read mode is used. * * For specifying flags and permission of file creation explicitly, * an array is used instead. * - * pid = spawn(command, STDIN=>["file"]) # read mode is assumed - * pid = spawn(command, STDIN=>["file", "r"]) - * pid = spawn(command, STDOUT=>["log", "w"]) # 0644 assumed - * pid = spawn(command, STDOUT=>["log", "w", 0600]) - * pid = spawn(command, STDOUT=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600]) + * pid = spawn(command, :in=>["file"]) # read mode is assumed + * pid = spawn(command, :in=>["file", "r"]) + * pid = spawn(command, :out=>["log", "w"]) # 0644 assumed + * pid = spawn(command, :out=>["log", "w", 0600]) + * pid = spawn(command, :out=>["log", File::WRONLY|File::EXCL|File::CREAT, 0600]) * * The array specifies a filename, flags and permission. * The flags can be a string or an integer. @@ -2977,26 +2977,26 @@ rb_f_system(int argc, VALUE *argv) * If an array of IOs and integers are specified as a hash key, * all the elemetns are redirected. * - * # standard output and standard error is redirected to log file. + * # stdout and stderr is redirected to log file. * # The file "log" is opened just once. - * pid = spawn(command, [STDOUT, STDERR]=>["log", "w"]) + * pid = spawn(command, [:out, :err]=>["log", "w"]) * * Another way to merge multiple file descriptors is [:child, fd]. * [:child, fd] means the file descriptor in the child process. * This is different from fd. - * For example, STDERR=>STDOUT means redirecting child STDERR to parent STDOUT. - * But STDERR=>[:child, STDOUT] means redirecting child STDERR to child STDOUT. - * They differs if STDOUT is redirected in the child process as follows. + * For example, :err=>:out means redirecting child stderr to parent stdout. + * But :err=>[:child, :out] means redirecting child stderr to child stdout. + * They differs if stdout is redirected in the child process as follows. * - * # standard output and standard error is redirected to log file. + * # stdout and stderr is redirected to log file. * # The file "log" is opened just once. - * pid = spawn(command, STDOUT=>["log", "w"], STDERR=>[:child, STDOUT]) + * pid = spawn(command, :out=>["log", "w"], :err=>[:child, :out]) * - * [:child, STDOUT] can be used to merge STDERR into STDOUT in IO.popen. - * In this case, IO.popen redirects STDOUT to a pipe in the child process - * and [:child, STDOUT] refers the redirected STDOUT. + * [:child, :out] can be used to merge stderr into stdout in IO.popen. + * In this case, IO.popen redirects stdout to a pipe in the child process + * and [:child, :out] refers the redirected stdout. * - * io = IO.popen(["sh", "-c", "echo out; echo err >&2", STDERR=>[:child, STDOUT]]) + * io = IO.popen(["sh", "-c", "echo out; echo err >&2", :err=>[:child, :out]]) * p io.read #=> "out\nerr\n" * * spawn closes all non-standard unspecified descriptors by default. @@ -3014,7 +3014,7 @@ rb_f_system(int argc, VALUE *argv) * * # similar to r = IO.popen(command) * r, w = IO.pipe - * pid = spawn(command, STDOUT=>w) # r, w is closed in the child process. + * pid = spawn(command, :out=>w) # r, w is closed in the child process. * w.close * * :close is specified as a hash value to close a fd individualy. @@ -3022,13 +3022,23 @@ rb_f_system(int argc, VALUE *argv) * f = open(foo) * system(command, f=>:close) # don't inherit f. * + * If a file descriptor need to be inherited, + * io=>io can be used. + * + * # valgrind has --log-fd option for log destination. + * # log_w=>log_w indicates log_w.fileno inherits to child process. + * log_r, log_w = IO.pipe + * pid = spawn("valgrind", "--log-fd=#{log_w.fileno}", "echo", "a", log_w=>log_w) + * log_w.close + * p log_r.read + * * It is also possible to exchange file descriptors. * - * pid = spawn(command, STDOUT=>STDERR, STDERR=>STDOUT) + * pid = spawn(command, :out=>:err, :err=>:out) * * The hash keys specify file descriptors in the child process. * The hash values specifies file descriptors in the parent process. - * So the above specifies exchanging STDOUT and STDERR. + * So the above specifies exchanging stdout and stderr. * Internally, +spawn+ uses an extra file descriptor to resolve such cyclic * file descriptor mapping. * |