Interval value of 0 to skip interval for speicific sources.

Update documentation to specify that intervals with value 0 are valid to skip an interval explicitly for a given source.

ccollect

@@ -765,7 +765,7 @@ while [ "${source_no}" -lt "${no_sources}" ]; do
         oldest_bak=$(ls -${TSORT}1r | grep "^${INTERVAL}\\." | head -n 1 || \
             _exit_err "Listing oldest backup failed")
         _techo "Using ${oldest_bak} for destination dir ${destination_dir}"
-        if mv "${oldest_bak}" "${destination_dir}"; then
+        if mv "${oldest_bak}" "${destination_dir}" 2>/dev/null; then
             # Touch dest dir so it is not sorted wrong in listings below.
             ls_rm_exclude=$(basename "${destination_dir}")
 
@@ -779,7 +779,7 @@ while [ "${source_no}" -lt "${no_sources}" ]; do
         if [ "${remove}" -gt 0 ]; then
             _techo "Removing ${remove} backup(s)..."
 
-            if [ -z "${ls_rm_exclude}" ]; then
+            if [ -z "${ls_rm_exclude}" -o ${c_interval} -eq 0 ]; then
                 # shellcheck disable=SC2010
                 ls -${TSORT}1r | grep "^${INTERVAL}\\." | head -n "${remove}" > "${TMP}" || \
                         _exit_err "Listing old backups failed"
@@ -793,6 +793,14 @@ while [ "${source_no}" -lt "${no_sources}" ]; do
         fi
     fi
 
+    #
+    # Skip backup of this source if interval is zero.
+    #
+    if [ ${c_interval} -eq 0 ]; then
+        _techo "Skipping backup for this interval."
+        exit 0
+    fi
+
     #
     # Check for backup directory to clone from: Always clone from the latest one!
     # Exclude destination_dir from listing, it can be touched reused and renamed

doc/ccollect.text

@@ -339,6 +339,9 @@ Example:
 --------------------------------------------------------------------------------
 This means to keep 28 daily backups, 12 monthly backups and 4 weekly.
 
+If you set a value of 0 the interval will be skipped. This is useful mainly on
+source level in order to skip a certain interval for a specific source.
+
 
 General pre- and post-execution
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -420,6 +423,12 @@ Example:
    /home/nico/vpn
 --------------------------------------------------------------------------------
 
+You can overwrite a default interval at source level. Setting it to 0 will skip
+this interval on a specific source allowing you to skip an interval for a
+specific source only while keeping source-specific interval amounts (or default
+values) for any other source.
+
+
 Default options
 ^^^^^^^^^^^^^^^
 If you add '$CCOLLECT_CONF/defaults/`option_name`', the value will