X-Git-Url: https://git.brokenzipper.com/gitweb?a=blobdiff_plain;f=tests%2Fincremen.sh;h=24868aaea09a499ea83fd0568901f117cf1b0945;hb=9e0d0592059515045e12e50e7fbad8271d243e14;hp=c723e9c9b66b2c2fc26cb64122373296865f28d6;hpb=70fdfd4fa136db573a473fcb30a6e2d8e58e5c72;p=chaz%2Ftar

diff --git a/tests/incremen.sh b/tests/incremen.sh
index c723e9c..24868aa 100755
--- a/tests/incremen.sh
+++ b/tests/incremen.sh
@@ -3,16 +3,31 @@
 
 . ./preset
 . $srcdir/before
+prereq gnu oldgnu
 
 set -e
 mkdir structure
-touch structure/file
-# FIXME: The sleep is necessary for the second tar to work.  Exactly why?
+echo x >structure/file
+
+# On Nextstep (and perhaps other 4.3BSD systems),
+# a newly created file's ctime isn't updated
+# until the next sync or stat operation on the file.
+ls -l structure/file >/dev/null
+
+# If the time of an initial backup and the creation time of a file contained
+# in that backup are the same, the file will be backed up again when an
+# incremental backup is done, because the incremental backup backs up
+# files created `on or after' the initial backup time.  Without the sleep
+# command, behaviour of tar becomes variable, depending whether the system
+# clock ticked over to the next second between creating the file and
+# backing it up.
 sleep 1
+
 tar cf archive --listed=list structure
 tar cfv archive --listed=list structure
 echo -----
-touch structure/file
+sleep 1
+echo y >structure/file
 tar cfv archive --listed=list structure
 
 out="\