1 files changed, 21 insertions, 33 deletions
diff --git a/lib/libc/gen/popen.3 b/lib/libc/gen/popen.3
index 9ca1bb3..01b0c2f 100644
--- a/lib/libc/gen/popen.3
+++ b/lib/libc/gen/popen.3
@@ -29,9 +29,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     @(#)popen.3	8.2 (Berkeley) 5/3/95
+.\"     @(#)popen.3	8.1 (Berkeley) 6/4/93
 .\"
-.Dd May 3, 1995
+.Dd June 4, 1993
 .Dt POPEN 3
 .Os
 .Sh NAME
@@ -50,32 +50,13 @@ The
 .Fn popen
 function
 .Dq opens
-a process by creating an IPC connection,
+a process by creating a pipe,
 forking,
 and invoking the shell.
-Historically,
-.Nm popen
-was implemented with a unidirectional pipe;
-hence many implementations of
-.Nm popen
-only allow the
+Since a pipe is by definition unidirectional, the
 .Fa type
-argument to specify reading or writing, not both.
-Since
-.Nm popen
-is now implemented using sockets, the
-.Fa type
-may request a bidirectional data flow.
-The
-.Fa type
-argument is a pointer to a null-terminated string
-which must be
-.Ql r
-for reading,
-.Ql w
-for writing, or
-.Ql r+
-for reading and writing.
+argument may specify only reading or writing, not both;
+the resulting stream is correspondingly read-only or write-only.
 .Pp
 The
 .Fa command
@@ -86,6 +67,15 @@ This command is passed to
 using the
 .Fl c
 flag; interpretation, if any, is performed by the shell.
+The
+.Fa mode
+argument is a pointer to a null-terminated string
+which must be either
+.Ql r
+for reading
+or
+.Ql w
+for writing.
 .Pp
 The return value from
 .Fn popen
@@ -123,10 +113,9 @@ The
 function returns
 .Dv NULL
 if the
-.Xr fork 2 ,
-.Xr pipe 2 ,
+.Xr fork 2
 or
-.Xr socketpair 2
+.Xr pipe 2
 calls fail,
 or if it cannot allocate memory.
 .Pp
@@ -150,13 +139,12 @@ The
 function does not reliably set
 .Va errno .
 .Sh SEE ALSO
-.Xr fork 2 ,
 .Xr sh 1 ,
+.Xr fork 2 ,
 .Xr pipe 2 ,
-.Xr socketpair 2 ,
 .Xr wait4 2 ,
-.Xr fflush 3 ,
 .Xr fclose 3 ,
+.Xr fflush 3 ,
 .Xr fopen 3 ,
 .Xr stdio 3 ,
 .Xr system 3
@@ -182,9 +170,9 @@ The
 .Fn popen
 argument
 always calls
-.Xr sh ,
+.Xr sh 1 ,
 never calls
-.Xr csh .
+.Xr csh 1 .
 .Sh HISTORY
 A
 .Fn popen