diff --git a/knowledge base/sort.md b/knowledge base/sort.md
index 183fa44..cdc3cde 100644
--- a/knowledge base/sort.md	
+++ b/knowledge base/sort.md	
@@ -14,4 +14,36 @@ sort -n path/to/file
 
 # Sort lines and remove duplicates.
 sort -u path/to/file
+
+# Sort by the value in the last field.
+awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt \
+  | sort -n -t '|' | awk -F '|' '{print $NF}'
 ```
+
+## Sort by the value in the last field
+
+1. copy the last field (column) of each line at the beginning of each of the lines with a different delimiter:
+
+   ```shell
+   awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt
+   ```
+
+1. sort on the 1st field specifing the delimiter to be the character above:
+
+   ```shell
+   awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt | sort -n -t '|'
+   ```
+
+1. discard the first field
+
+   ```shell
+   awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt | sort -n -t '|' | awk -F '|' '{print $NF}'
+   awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt | sort -n -t '|' | awk -F '|' '{print $2}'
+   awk 'BEGIN {FS=","; OFS="|"} {print $NF,$0}' file.txt | sort -n -t '|' | cut -d '|' -f 2
+   ```
+
+## Sources
+
+- [Sort a file in Unix based on the last field]
+
+[sort a file in unix based on the last field]: http://www.unixcl.com/2010/11/sort-file-based-on-last-field-unix.html