diff options
Diffstat (limited to 'man2/select_tut.2')
| -rw-r--r-- | man2/select_tut.2 | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/man2/select_tut.2 b/man2/select_tut.2 index e860de3..cbb6953 100644 --- a/man2/select_tut.2 +++ b/man2/select_tut.2 @@ -9,7 +9,7 @@ .\" various other changes .\" 2008-01-26, mtk, substantial changes and rewrites .\" -.TH SELECT_TUT 2 2023-05-03 "Linux man-pages 6.05.01" +.TH SELECT_TUT 2 2023-10-31 "Linux man-pages 6.7" .SH NAME select, pselect \- synchronous I/O multiplexing .SH LIBRARY @@ -27,7 +27,7 @@ system calls are used to efficiently monitor multiple file descriptors, to see if any of them is, or becomes, "ready"; that is, to see whether I/O becomes possible, or an "exceptional condition" has occurred on any of the file descriptors. -.PP +.P This page provides background and tutorial information on the use of these system calls. For details of the arguments and semantics of @@ -54,7 +54,7 @@ This behavior is essential so that signals can be processed in the main loop of the program, otherwise .BR select () would block indefinitely. -.PP +.P Now, somewhere in the main loop will be a conditional to check the global flag. So we must ask: @@ -82,7 +82,7 @@ call would enable .B SIGCHLD by using an empty signal mask. Our program would look like: -.PP +.P .EX static volatile sig_atomic_t got_SIGCHLD = 0; \& @@ -310,7 +310,7 @@ can be used to solve many problems in a portable and efficient way that naive programmers try to solve in a more complicated manner using threads, forking, IPCs, signals, memory sharing, and so on. -.PP +.P The .BR poll (2) system call has the same functionality as @@ -319,7 +319,7 @@ and is somewhat more efficient when monitoring sparse file descriptor sets. It is nowadays widely available, but historically was less portable than .BR select (). -.PP +.P The Linux-specific .BR epoll (7) API provides an interface that is more efficient than @@ -332,7 +332,7 @@ Here is an example that better demonstrates the true utility of .BR select (). The listing below is a TCP forwarding program that forwards from one TCP port to another. -.PP +.P .\" SRC BEGIN (select.c) .EX #include <arpa/inet.h> @@ -604,7 +604,7 @@ main(int argc, char *argv[]) } .EE .\" SRC END -.PP +.P The above program properly forwards most kinds of TCP connections including OOB signal data transmitted by \fBtelnet\fP servers. It handles the tricky problem of having data flow in both directions @@ -617,7 +617,7 @@ Another idea is to set nonblocking I/O using .BR fcntl (2). This also has its problems because you end up using inefficient timeouts. -.PP +.P The program does not handle more than one simultaneous connection at a time, although it could easily be extended to do this with a linked list of buffers\[em]one for each connection. |