Hello all,
the manual page of GNU gzip says:
------------------------------DIAGNOSTICS       Exit status is normally 0; if an error occurs, exit status is 1. If a warning occurs, exit status is 2.------------------------------
This is not the case sind version >1.5 for the situation when the source file already ends with .gz 
Test:
$ gzip 2018.gzgzip: 2018.gz already has .gz suffix -- unchanged$ echo $?0
Following the patch for it:
diff --git a/gzip.c b/gzip.cindex e6a7761..bf3eb0a 100644--- a/gzip.c+++ b/gzip.c@@ -1417,8 +1417,8 @@ local int make_ofname()         /* Avoid annoying messages with -r (see treat_dir()) */         if (verbose || (!recursive && !quiet)) {             /* Don't use WARN, as it affects exit status.  */-            fprintf (stderr, "%s: %s already has %s suffix -- unchanged\n",-                     program_name, ifname, suff);+            WARN ((stderr, "%s: %s already has %s suffix -- unchanged\n",+                     program_name, ifname, suff));         }         return WARNING;     } else {
Test:
$ gzip 2018.gzgzip: 2018.gz already has .gz suffix -- unchanged$ echo $?2
Best regards,Manfred