JLine error when attempting to run the REPL with piped input

[deanwampler]

Scala 3.0.0-RC2. A command like the following:

$ scala <<EOF
:load somestuff.scala
EOF

or trying:

$ echo ":load src/script/scala/progscala3/hierarchy/Asserts.scala" | scala

Both cause this exception:

Exception in thread "main" java.lang.IllegalStateException: Unable to create a system terminal
	at org.jline.terminal.TerminalBuilder.doBuild(TerminalBuilder.java:323)
	at org.jline.terminal.TerminalBuilder.build(TerminalBuilder.java:265)
	at dotty.tools.repl.JLineTerminal.<init>(JLineTerminal.scala:23)
	at dotty.tools.repl.ReplDriver.runUntilQuit(ReplDriver.scala:123)
	at dotty.tools.repl.ReplDriver.tryRunning(ReplDriver.scala:114)
	at dotty.tools.repl.Main$.main(Main.scala:6)
	at dotty.tools.repl.Main.main(Main.scala)

This is fairly well known issue, see for example https://youtrack.jetbrains.com/issue/IDEA-183619. I attempted to use the recommended fix, setting the property -Dorg.jline.terminal.dumb=true. I did this by passing the argument -J-Dorg.jline.terminal.dumb=true to the REPL, even though this argument is not documented for the REPL in the -help output. It appeared to be ignored or do nothing. I also tried setting the environment variable JAVA_OPTS=-Dorg.jline.terminal.dumb=true before starting the REPL, but that didn't work either. Finally, I even tried setting the property inside the REPL, i.e.,

$ scala <<EOF
System.setProperty("...", "...")
:load somestuff.scala
EOF

I would expect this to be too late. It also doesn't help.

Note that in the Scala 2.13 REPL, without setting the property, you get a warning that it will default to a dumb terminal, but otherwise appears to work fine.

[griggt]

These incantations using TERM=dumb seem to work (at least on Linux)

$ TERM=dumb scala <<EOF
:load somestuff.scala
EOF

$ echo ":load src/script/scala/progscala3/hierarchy/Asserts.scala" | TERM=dumb scala

But we should probably gracefully fall back to a dumb terminal like Scala 2 does, as was also suggested here.

[deanwampler]

I just noticed in #11707 that using TERM=dumb should work. I confirmed it works on MacOS, too, just now. Thanks!

[catap]

Interesting that without TERM=dumb it simple doesn't work on OpenBSD

[catap]

#19744 may fixe this