Issue #4477 has been updated by schneems (Richard Schneeman). Just found out about this behavior today when this code ``` out = `command -v ruby` ``` Works on my mac but not on linux (github actions) with an error `Errno::ENOENT: No such file or directory - command`. That is because on my mac `command` is ALSO on the PATH, but on linux it is not. I could fix it by adding a redirect ``` out = `command -v ruby 2>/dev/null` ``` Which triggers the shell behavior. I find it surprising that exec mentions this behavior https://www.rubydoc.info/stdlib/core/Kernel:exec but backticks https://ruby-doc.org/3.4.1/Kernel.html#method-i-60 doesn't. ---------------------------------------- Feature #4477: Kernel:exec and backtick (`) don't work for certain system commands https://bugs.ruby-lang.org/issues/4477#change-116537 * Author: JWuttke (Joachim Wuttke) * Status: Closed * Assignee: akr (Akira Tanaka) ---------------------------------------- From documentation and common sense, I would expect that Kernel:exec and backtick (`) work for _all_ kind of system commands. This is currently not the case. ~$ cat test1 echo success ~$ cat test2 #!/bin/sh echo success ~$ chmod a+x test? ~$ ruby1.8 -e 'p `test1`' -e:1: command not found: test1 "" ~$ ruby1.9 -e 'p `test1`' -e:1:in ``': Exec format error - test1 (Errno::ENOEXEC) from -e:1:in `<main>' ~$ ruby1.8 -e 'p `test2`' "success\n" ~$ ruby1.9 -e 'p `test2`' "success\n" This problem has been reported before (#3856: strange Kernel#exec behavior with bash's source command). As a workaround, it has been suggested to append a semikolon to the system command: ~$ ruby1.8 -e 'p `test1;`' "success\n" ~$ ruby1.9 -e 'p `test1;`' "success\n" The report #3856 has been closed with the decision "not a bug". This I cannot accept. For many years, I got used to run system commands through `<cmd>`. When it failed, I spent painfully long time to search for a bug in my Ruby code and in the system command before I realized the problem was due to an unexpected restriction of Ruby's exec/backtick. -- https://bugs.ruby-lang.org/