docs: update

1 files changed, 18 insertions, 0 deletions

diff --git a/README.md b/README.md
index 42ba1f3..0628f5c 100644
--- a/README.md
+++ b/README.md
@@ -139,7 +139,15 @@ removing it from the start and end of the string.
 ```sh
 trim_string() {
     # Usage: trim_string "   example   string    "
+
+    # Remove all leading white-space.
+    # '${1%%[![:space:]]*}': Strip everything but leading white-space.
+    # '${1#${XXX}}': Remove the white-space from the start of the string.
     trim=${1#${1%%[![:space:]]*}}
+
+    # Remove all trailing white-space.
+    # '${trim##*[![:space:]]}': Strip everything but trailing white-space.
+    # '${trim#${XXX}}': Remove the white-space from the end of the string.
     trim=${trim%${trim##*[![:space:]]}}
 
     printf '%s\n' "$trim"
@@ -169,9 +177,19 @@ without leading/trailing white-space and with truncated spaces.
 # shellcheck disable=SC2086,SC2048
 trim_all() {
     # Usage: trim_all "   example   string    "
+
+    # Disable globbing to make the word-splitting below safe.
     set -f
+
+    # Set the argument list to the word-splitted string.
+    # This removes all leading/trailing white-space and reduces
+    # all instances of multiple spaces to a single ("  " -> " ").
     set -- $*
+
+    # Print the argument list as a string.
     printf '%s\n' "$*"
+
+    # Re-enable globbing.
     set +f
 }
 ```