bin/ifnew: Add -v flag

1 files changed, 19 insertions, 5 deletions

diff --git a/bin/ifnew b/bin/ifnew
index 2a72922..f4a4120 100755
--- a/bin/ifnew
+++ b/bin/ifnew
@@ -4,7 +4,7 @@ set -eu
 usage() {
 	cat <<-'EOF'
 		Usage:
-		  ifnew FILE
+		  ifnew [-v] FILE
 		  ifnew -h
 	EOF
 }
@@ -14,13 +14,15 @@ help() {
 
 
 		Options:
+		  -v            notify when new
 		  -h, --help    show this message
 
 		  FILE          the target to compared against
 
 
 		Compare STDIN to FILE, and only write to FILE if STDIN content
-		differs from FILE content.
+		differs from FILE content.  When -v is given, notify on STDERR
+		that FILE has new content (useful for debugging purposes).
 
 
 		Examples:
@@ -41,10 +43,11 @@ help() {
 		    # timestamp 2
 
 
-		  Only change file when content changes in a Makefile:
+		  Only change file when content changes in a Makefile, and print
+		  to STDERR when it does:
 
 		    i18.cfg: ALWAYS
-			gen-cfg | ifnew $@
+			gen-cfg | ifnew -v $@
 			po4a $@
 	EOF
 }
@@ -65,8 +68,12 @@ for flag in "$@"; do
 	esac
 done
 
-while getopts 'h' flag; do
+VERBOSE=false
+while getopts 'vh' flag; do
 	case "$flag" in
+		v)
+			VERBOSE=true
+			;;
 		h)
 			usage
 			help
@@ -89,5 +96,12 @@ trap 'rm -f "$STDIN"' EXIT
 
 cat - > "$STDIN"
 if ! cmp -s "$STDIN" "$FILE"; then
+	if [ "$VERBOSE" = true ]; then
+		printf 'ifnew: "%s" will be updated.\n' "$FILE" >&2
+	fi
 	mv "$STDIN" "$FILE"
+else
+	if [ "$VERBOSE" = true ]; then
+		printf 'ifnew: "%s" left unchanged.\n' "$FILE" >&2
+	fi
 fi