cp,mv: add --update=none to always skip existing files

Add --update=none which is equivalent to the --no-clobber behavior
from before coreutils 9.2.  I.e. existing files are unconditionally
skipped, and them not being replaced does not affect the exit status.

* src/copy.h [enum Update_type]: A new type to support parameters
to the --update command line option.
[enum Interactive]: Add I_ALWAYS_SKIP.
* src/copy.c: Treat I_ALWAYS_SKIP like I_ALWAYS_NO (-n),
except that we don't fail when skipping.
* src/system.h (emit_update_parameters_note): A new function
to output the description of the new --update parameters.
* src/cp.c (main): Parse --update arguments, ensuring that
-n takes precedence if specified.
(usage): Describe the new option.  Also allude that
-u is related in the -n description.
* src/mv.c: Accept the new --update parameters and
update usage() accordingly.
* doc/coreutils.texi (cp invocation): Describe the new --update
parameters.  Also reference --update from the --no-clobber description.
(mv invocation): Likewise.
* tests/mv/update.sh: Test the new parameters.
* NEWS: Mention the new feature.
Addresses https://bugs.gnu.org/62572

1 files changed, 31 insertions, 16 deletions

diff --git a/tests/mv/update.sh b/tests/mv/update.sh
index d3ec6120c..ab7309f06 100755
--- a/tests/mv/update.sh
+++ b/tests/mv/update.sh
@@ -19,11 +19,13 @@
 . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
 print_ver_ cp mv
 
-echo old > old || framework_failure_
-touch -d yesterday old || framework_failure_
-echo new > new || framework_failure_
-
+test_reset() {
+  echo old > old || framework_failure_
+  touch -d yesterday old || framework_failure_
+  echo new > new || framework_failure_
+}
 
+test_reset
 for interactive in '' -i; do
   for cp_or_mv in cp mv; do
     # This is a no-op, with no prompt.
@@ -36,19 +38,32 @@ for interactive in '' -i; do
   done
 done
 
-# This will actually perform the rename.
-mv --update new old || fail=1
-test -f new && fail=1
-case "$(cat old)" in new) ;; *) fail=1 ;; esac
+# These should perform the rename / copy
+for update_option in '--update' '--update=older' '--update=all' \
+ '--update=none --update=all'; do
+  test_reset
+  mv $update_option new old || fail=1
+  test -f new && fail=1
+  case "$(cat old)" in new) ;; *) fail=1 ;; esac
+
+  test_reset
+  cp $update_option new old || fail=1
+  case "$(cat old)" in new) ;; *) fail=1 ;; esac
+  case "$(cat new)" in new) ;; *) fail=1 ;; esac
+done
 
-# Restore initial conditions.
-echo old > old || framework_failure_
-touch -d yesterday old || fail=1
-echo new > new || framework_failure_
+# These should not perform the rename / copy
+for update_option in '--update=none' \
+ '--update=all --update=none'; do
+  test_reset
+  mv $update_option new old || fail=1
+  case "$(cat new)" in new) ;; *) fail=1 ;; esac
+  case "$(cat old)" in old) ;; *) fail=1 ;; esac
 
-# This will actually perform the copy.
-cp --update new old || fail=1
-case "$(cat old)" in new) ;; *) fail=1 ;; esac
-case "$(cat new)" in new) ;; *) fail=1 ;; esac
+  test_reset
+  cp $update_option new old || fail=1
+  case "$(cat new)" in new) ;; *) fail=1 ;; esac
+  case "$(cat old)" in old) ;; *) fail=1 ;; esac
+done
 
 Exit $fail