added -k parameter to sort by columns

lib/sort.go

@@ -0,0 +1,46 @@
+/*
+Copyright © 2022 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package lib
+
+import (
+	"sort"
+)
+
+func sortTable(data *Tabdata, col int) {
+	if col <= 0 {
+		// no sorting wanted
+		return
+	}
+
+	col-- // ui starts counting by 1, but use 0 internally
+
+	// sanity checks
+	if len(data.entries) == 0 {
+		return
+	}
+
+	if col >= len(data.headers) {
+		// fall back to default column
+		col = 0
+	}
+
+	// actual sorting
+	sort.SliceStable(data.entries, func(i, j int) bool {
+		return data.entries[i][col] < data.entries[j][col]
+	})
+}