Environment Information

Provide at least:

• JRuby version (jruby -v) and command line (flags, JRUBY_OPTS, etc)

  jruby 10.0.2.0 (3.4.2) 2025-08-07 cba6031bd0 OpenJDK 64-Bit Server VM 26-ea+17-Ubuntu-1 on 26-ea+17-Ubuntu-1 +indy +jit [aarch64-linux]
  

• Operating system and platform (e.g. uname -a)

  Linux adequate-kid 6.17.0-5-generic #5-Ubuntu SMP PREEMPT_DYNAMIC Mon Sep 22 09:50:31 UTC 2025 aarch64 aarch64 aarch64 GNU/Linux
  

Other relevant info you may wish to add:

• Installed or activated gems
• Application/framework version (e.g. Rails, Sinatra)
• Environment variables
  PAGER='less -RSs'

Expected Behavior

• Describe your expectation of how JRuby should behave, perhaps by showing how CRuby/MRI behaves.
  LESS='less -RSs' ruby --help sends the help message to the pager, less with -RSs option.
  jruby should do similarly.

• Provide an executable Ruby script or a link to an example repository.

Actual Behavior

• Describe or show the actual behavior.

  $ LESS='less -RSs' jruby --help
  java.io.IOException: Cannot run program "less -RSs": error=2, No such file or directory
  	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1170)
  	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1089)
  	at org.jruby.dist/org.jruby.Main.doPrintUsage(Main.java:475)
  	at org.jruby.dist/org.jruby.Main.internalRun(Main.java:252)
  	at org.jruby.dist/org.jruby.Main.run(Main.java:227)
  	at org.jruby.dist/org.jruby.Main.main(Main.java:199)
  Caused by: java.io.IOException: error=2, No such file or directory
  	at java.base/java.lang.ProcessImpl.forkAndExec(Native Method)
  	at java.base/java.lang.ProcessImpl.<init>(ProcessImpl.java:295)
  	at java.base/java.lang.ProcessImpl.start(ProcessImpl.java:225)
  	at java.base/java.lang.ProcessBuilder.start(ProcessBuilder.java:1126)
  	... 5 more

• Provide text or screen capture showing the behavior.