From eb884b43723710e0c126c07f40648831b42db261 Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@drexel.edu>
Date: Fri, 2 Dec 2011 10:14:27 -0500
Subject: [PATCH] Add checks for required utilities to name-by-date.sh.

---
 posts/name-by-date/name-by-date.sh | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/posts/name-by-date/name-by-date.sh b/posts/name-by-date/name-by-date.sh
index a4784bc..57feb2e 100755
--- a/posts/name-by-date/name-by-date.sh
+++ b/posts/name-by-date/name-by-date.sh
@@ -2,7 +2,7 @@
 #
 # Rename JPEGs to reflect the creation date stored in their metadata.
 #
-# Copyright (C) 2010 W. Trevor King <wking@drexel.edu>
+# Copyright (C) 2010-2011 W. Trevor King <wking@drexel.edu>
 #
 # 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
@@ -20,36 +20,43 @@
 #
 #
 # usage: name-by-date.sh $(find . -name '*.jpg')
-#
-# uses exif, [, cut, dirname, echo, file, grep, let, mv, and sed.
+
+# check for required utilities
+DIRNAME=$(which dirname) || exit 1
+EXIF=$(which exif) || exit 1
+FILE_=$(which file) || exit 1
+GREP=$(which grep) || exit 1
+MV=$(which mv) || exit 1
+SED=$(which sed) || exit 1
+TEST=$(which '[') || exit 1  # but I just use [ in the script
 
 
 while [ -n "$1" ]; do
 	FILE=$1
-	TYPE=$(file "$FILE" | grep JPEG)
+	TYPE=$("${FILE_}" "$FILE" | "${GREP}" JPEG)
 	if [ -n "$TYPE" ]; then
 		FIELD_NAME="$NAME_BY_DATE_FIELD_NAME"
 		if [ -z "$FIELD_NAME" ]; then
 				FIELD_NAME='Date and Time'
 		fi
-		ASCII_DATE=$(exif -m -t "$FIELD_NAME" "$FILE")  # 2010:07:02 08:36:20
+		ASCII_DATE=$("${EXIF}" -m -t "$FIELD_NAME" "$FILE")  # 2010:07:02 08:36:20
 		if [ $? -ne 0 ]; then  # use similar field, e.g. 'Date and Time (original)'
-			FIELD=$(exif -m "$FILE" | grep "$FIELD_NAME" | head -n1)
-			FIELD_NAME=$(echo "$FIELD" | sed 's/\t.*//')
+			FIELD=$("${EXIF}" -m "$FILE" | "${GREP}" "$FIELD_NAME" | head -n1)
+			FIELD_NAME=$(echo "$FIELD" | "${SED}" 's/\t.*//')
 			if [ -z "$FIELD_NAME" ]; then
 				echo "$FILE has no stored date"
 				ASCII_DATE=""
 			else
 				echo "$FILE using date from $FIELD_NAME"
-				ASCII_DATE=$(exif -m -t "$FIELD_NAME" "$FILE")  # 2010:07:02 08:36:20
+				ASCII_DATE=$("${EXIF}" -m -t "$FIELD_NAME" "$FILE")  # 2010:07:02 08:36:20
 			fi
 		fi
-		DATE=$(echo "$ASCII_DATE" | sed 's/:/./g' | sed 's/ /./g')
+		DATE=$(echo "$ASCII_DATE" | "${SED}" 's/:/./g' | "${SED}" 's/ /./g')
 		if [ -z "$DATE" ]; then
 			echo "$FILE has no stored date"
 	 	else
 			echo "$FILE taken on \"$DATE\""
-			FILE_DIR=$(dirname "$FILE")
+			FILE_DIR=$("${DIRNAME}" "$FILE")
 			NEW_NAME="$FILE_DIR/$DATE.jpg"
 			if [ -e "$NEW_NAME" ] && [ "$NEW_NAME" != "$FILE" ]; then
 				i=1
@@ -61,7 +68,7 @@ while [ -n "$1" ]; do
 				done
 			fi
 			if [ "$NEW_NAME" != "$FILE" ]; then
-				mv "$FILE" "$NEW_NAME"
+				"${MV}" "$FILE" "$NEW_NAME"
 			fi
 		fi
 	fi
-- 
2.26.2