Tomcat startup script output not available with piping (grep)

Question

I'm completely puzzled by this behavior of Tomcat 9.0.21 startup script catalina.sh:

# following line added by me
echo "CATALINA_HOME"
# following line added by me
echo $have_tty

if [ $have_tty -eq 1 ]; then
  # following line added by me
  echo "CATALINA_HOME"

  echo "Using CATALINA_BASE:   $CATALINA_BASE"
  echo "Using CATALINA_HOME:   $CATALINA_HOME"
  echo "Using CATALINA_TMPDIR: $CATALINA_TMPDIR"
  if [ "$1" = "debug" ] ; then
    echo "Using JAVA_HOME:       $JAVA_HOME"
  else
    echo "Using JRE_HOME:        $JRE_HOME"
  fi
  echo "Using CLASSPATH:       $CLASSPATH"
  if [ ! -z "$CATALINA_PID" ]; then
    echo "Using CATALINA_PID:    $CATALINA_PID"
  fi
fi

Now when I run catalina version | grep CATALINA_HOME I cannot see any result with the original script version. In my modified version of script I can only see what's echo-ed before the 'if have_tty' section!

catalina | grep CATALINA
CATALINA_HOME

I'd expect to see also the next CATALINA_HOME echo-ed from within the if block as well as the "Using CATALINA_HOME ..." line.

What's going on there?

(If it matters I'm running Mac OS X 10.14.5 with iTerm and zsh as my shell)

UPDATE

People commented that it's because the have_tty variable isn't set but that's not a problem in my case. When I just run catalina version I get the full output:

CATALINA_HOME
1
CATALINA_HOME
Using CATALINA_BASE:   /usr/local/Cellar/tomcat/9.0.21/libexec
Using CATALINA_HOME:   /usr/local/Cellar/tomcat/9.0.21/libexec
Using CATALINA_TMPDIR: /usr/local/Cellar/tomcat/9.0.21/libexec/temp
Using JRE_HOME:        /Users/jumar/.jenv/versions/1.8.0.171
Using CLASSPATH:       /usr/local/Cellar/tomcat/9.0.21/libexec/bin/bootstrap.jar:/usr/local/Cellar/tomcat/9.0.21/libexec/bin/tomcat-juli.jar
Server version: Apache Tomcat/9.0.21
...

It's just with the pipe (grep) that things start looking weird:

catalina version | grep CATALINA_HOME
CATALINA_HOME
# here should be the missing "Using CATALINA_HOME..."

Answer 1

First thanks to @Zeitounator and @A.B for their comments!

After some testing on different tomcat versions and digging deeper I've found, that indeed the issue is in have_tty being set to zero. Using the catalina script in the pipe makes the if [ -t 1 ]; test fail.

I was puzzled because using plain catalina sets have_tty properly to 1. It was even weirder because it used to work with previous minor tomcat version. It was in fact introduced in this commit: https://github.com/apache/tomcat/commit/bf894a0e6b5c8f92b122452645e93d63277ad3ab

It seems that the -t 1 test isn't appropriate when used in a pipe. Instead, it should be -t 0 (this is per A.B's comment "Usually the test is done on stdin").

Answer 2

Remove the | grep CATALINA from your test command and if you're not getting any output from the line:

echo $have_tty

Then $have_tty is not set and would then cause execution to not enter the if block. You would have to trace where $have_tty is getting set originally.

It looks like catalina uses this command to determine if it has a tty:

$ tty
/dev/ttys011

To get a tty, be sure the script is run from the command line and not through a non-tty process (e.g. init process)