libCom: Added echo command to iocsh

documentation/RELEASE_NOTES.html

@@ -15,6 +15,13 @@ EPICS Base 3.15.0.x releases are not intended for use in production systems.</p>
 <h2 align="center">Changes between 3.15.0.1 and 3.15.0.2</h2>
 <!-- Insert new items immediately below here ... -->
 
+<h3>Added echo command to iocsh</h3>
+
+<p>The single argument string may contain escaped characters, which will be
+translated to their raw form before being printed (enclose the string in quotes
+to avoid double-translation). A newline is always appended to the output, and
+output stream redirection is supported.</p>
+
 <h3>Added macro EPICS_UNUSED to compilerDependencies.h</h3>
 
 <p>To prevent the compiler from warning about a known-unused variable, mark it

src/libCom/iocsh/libComRegister.c

@@ -13,6 +13,7 @@
 #define epicsExportSharedSymbols
 #include "iocsh.h"
 #include "epicsStdioRedirect.h"
+#include "epicsString.h"
 #include "epicsTime.h"
 #include "epicsThread.h"
 #include "epicsMutex.h"
@@ -50,6 +51,17 @@ static void dateCallFunc (const iocshArgBuf *args)
     date(args[0].sval);
 }
 
+/* echo */
+static const iocshArg echoArg0 = { "string",iocshArgString};
+static const iocshArg * const echoArgs[1] = {&echoArg0};
+static const iocshFuncDef echoFuncDef = {"echo",1,echoArgs};
+static void echoCallFunc(const iocshArgBuf *args)
+{
+    char *str = args[0].sval;
+
+    dbTranslateEscape(str, str); /* in-place is safe */
+    printf("%s\n", str);
+}
 
 /* chdir */
 static const iocshArg chdirArg0 = { "directory name",iocshArgString};
@@ -348,6 +360,7 @@ static void installLastResortEventProviderCallFunc(const iocshArgBuf *args)
 void epicsShareAPI libComRegister(void)
 {
     iocshRegister(&dateFuncDef, dateCallFunc);
+    iocshRegister(&echoFuncDef, echoCallFunc);
     iocshRegister(&chdirFuncDef, chdirCallFunc);
     iocshRegister(&pwdFuncDef, pwdCallFunc);