Added instructions for the two-sided option.

fbopt

@@ -46,8 +46,9 @@ Options:
     -t, --two-sided                     toggle preserve the order in
                                         double sided paper: scan a batch of
                                         papers one side, then the other
-    --two-sided-reverse                 same as '--odd-even' but with the need of
-                                        reversing every single paper.
+    --two-sided-reverse                 same as '--two-sided' but with the need of
+                                        reversing every single paper. This
+                                        option conflicts with '--two-sided'
     -u, --unpaper[=OPTIONS]             enable unpaper. You may pass
                                         options to unpaper
 
@@ -182,6 +183,10 @@ main()
 
     # From now on you should call a function or an external program
     # using the values of the flag variables.
+    [ "${two_sided}" = 'true' ] \
+        && [ "${two_sided_reverse}" = 'true' ] \
+        && getopt_error \
+        && return 1
     [ "${list_modes}" = 'true' ] \
         && get_supported_modes "$(get_supported_parameters)" \
         && return ${?}
@@ -191,6 +196,8 @@ main()
     [ "${list_sources}" = 'true' ] \
         && get_supported_sources "$(get_supported_parameters)" \
         && return ${?}
+    # Override two_sided value if necessary.
+    [ "${two_sided_reverse}" = 'true' ] && two_sided='reverse'
 
     local output_file="${1}"
     [ -z "${output_file}" ] && getopt_error && return 1
@@ -201,6 +208,7 @@ main()
         "${resolution}" \
         "${source}" \
         "${unpaper}" \
+        "${two_sided}" \
         "${output_file}"
 }
 

spectrscan

@@ -40,20 +40,29 @@ check_software()
         pamfix
 } 1>/dev/null 2>/dev/null
 
-scan()
+get_last_page_side_a()
 {
-    local file_counter="${1}"
-
-    local batch_start=1
-    local batch_increment=1
+    ls spectrscan_out*.pnm | sort --reverse | head -n1 | tr -d [a-z]._
+}
 
-    if [ "$file_counter" = "odd" ]; then
-        batch_start=1
-        batch_increment=2
-    elif [ "$file_counter" = "even" ]; then
+scan()
+{
+    if [ "${two_sided}" = 'true' ] && [ "${side_b}" = 'true' ]; then
+        # side_b
+        batch_start=$(("$(get_last_page_side_a)"+1))
+        batch_increment=-2
+    elif [ "${two_sided}" = 'reverse' ] && [ "${side_b}" = 'true' ]; then
+        # side_b
         batch_start=2
         batch_increment=2
-    else
+    fi
+    if [ "${two_sided}" != 'false' ] && [ "${side_a}" = 'true' ]; then
+        # true, reverse, first side.
+        batch_start=1
+        batch_increment=2
+    fi
+    if [ "${two_sided}" = 'false' ]; then
+        # single sided
         batch_start=1
         batch_increment=1
     fi
@@ -211,20 +220,31 @@ chain()
     mkdir "$TMP_DIR"
     pushd "$TMP_DIR"
 
-    if [ "$odd_even" = 'true' ]; then
-        scan "odd" \
+    if [ "${two_sided}" = 'true' ]; then
+        side_a='true'
+        scan \
             && printf "%s\n" 'turn the paper(s) and hit return when ready' \
             && read \
-            && scan "even"
+            && side_a='false' \
+            && side_b='true' \
+            && scan
+    elif [ "${two_sided}" = 'reverse' ]; then
+        side_a='true'
+        scan \
+            && printf "%s\n" 'turn the paper(s) and hit return when ready' \
+            && read \
+            && side_a='false' \
+            && side_b='true' \
+            && scan
     else
         scan
     fi
 
-    # Feeder out of documents.
-    if [ ${?} -eq 7 ]; then
-        cleanup
-        return 1
-    fi
+    # Feeder out of documents unexpectedly.
+#    if [ ${?} -eq 7 ]; then
+#        cleanup
+#        return 1
+#    fi
 
     pnm_to_pdf
     pdf_cat
@@ -241,15 +261,16 @@ preliminary_checks()
     resolution="${3}"
     source="${4}"
     unpaper_options="${5}"
-    output_file="${6}"
+    two_sided="${6}"
+    output_file="${7}"
     # Get the parameters and check that the scanner is connected.
     supported_params="$(get_supported_parameters)"
 
     [ ${?} -ne 0 ] && return ${?}
 
-    { check_supported_parameters "modes" "${mode}" \
-        && check_supported_parameters "resolutions" "${resolution}" \
-        && check_supported_parameters "sources" "${source}"; } \
+    { check_supported_parameters 'modes' "${mode}" \
+        && check_supported_parameters 'resolutions' "${resolution}" \
+        && check_supported_parameters 'sources' "${source}"; } \
         || return 1
 
     chain