improve exit code use in bin scripts

The use of exit codes and exit code ranges has been
made more consistent across most bin tools.

bin/gen-year-index.sh

@@ -51,7 +51,7 @@ shopt -s globstar	# enable ** to match all files and zero or more directories an
 
 # set variables referenced in the usage message
 #
-export VERSION="1.0 2024-02-12"
+export VERSION="1.0.1 2024-02-23"
 NAME=$(basename "$0")
 export NAME
 export V_FLAG=0
@@ -59,7 +59,7 @@ GIT_TOOL=$(type -P git)
 export GIT_TOOL
 if [[ -z "$GIT_TOOL" ]]; then
     echo "$0: FATAL: git tool is not installed or not in \$PATH" 1>&2
-    exit 210
+    exit 5
 fi
 "$GIT_TOOL" rev-parse --is-inside-work-tree >/dev/null 2>&1
 status="$?"
@@ -106,15 +106,14 @@ export USAGE="usage: $0 [-h] [-v level] [-V] [-d topdir] [-n] [-N]
 
 Exit codes:
      0         all OK
+     1	       some internal tool exited non-zero
      2         -h and help string printed or -V and version string printed
      3         command line error
      4         bash version is < 4.2
-     5	       YYYY is not a year directory
-     6	       subst.year-navbar.awk tool or pandoc wrapper not found
-     7	       cannot find a non-empty or read .year file
-     8	       .year file under year YYYY is not a non-empty readable file
- >= 10  < 210  ((not used))
- >= 210	       internal tool error
+     5	       some internal tool is not found or not an executable file
+     6	       problems found with or in the topdir or topdir/YYYY directory
+     7	       problems found with or in the entry topdir/YYYY/dir directory
+ >= 10         internal error
 
 $NAME version: $VERSION"
 
@@ -244,28 +243,28 @@ export REPO_NAME
 if [[ -z $TOPDIR ]]; then
     echo "$0: ERROR: cannot find top of git repo directory" 1>&2
     echo "$0: Notice: if needed: $GIT_TOOL clone $REPO_URL; cd $REPO_NAME" 1>&2
-    exit 211
+    exit 6
 fi
 if [[ ! -e $TOPDIR ]]; then
     echo "$0: ERROR: TOPDIR does not exist: $TOPDIR" 1>&2
     echo "$0: Notice: if needed: $GIT_TOOL clone $REPO_URL; cd $REPO_NAME" 1>&2
-    exit 212
+    exit 6
 fi
 if [[ ! -d $TOPDIR ]]; then
     echo "$0: ERROR: TOPDIR is not a directory: $TOPDIR" 1>&2
     echo "$0: Notice: if needed: $GIT_TOOL clone $REPO_URL; cd $REPO_NAME" 1>&2
-    exit 213
+    exit 6
 fi
 
 # cd to topdir
 #
 if [[ ! -e $TOPDIR ]]; then
     echo "$0: ERROR: cannot cd to non-existent path: $TOPDIR" 1>&2
-    exit 217
+    exit 6
 fi
 if [[ ! -d $TOPDIR ]]; then
     echo "$0: ERROR: cannot cd to a non-directory: $TOPDIR" 1>&2
-    exit 218
+    exit 6
 fi
 export CD_FAILED
 if [[ $V_FLAG -ge 5 ]]; then
@@ -274,7 +273,7 @@ fi
 cd "$TOPDIR" || CD_FAILED="true"
 if [[ -n $CD_FAILED ]]; then
     echo "$0: ERROR: cd $TOPDIR failed" 1>&2
-    exit 219
+    exit 6
 fi
 if [[ $V_FLAG -ge 3 ]]; then
     echo "$0: debug[3]: now in directory: $(/bin/pwd)" 1>&2
@@ -284,11 +283,11 @@ fi
 #
 if [[ ! -d $YYYY ]]; then
     echo "$0: ERROR: arg is not a directory: $YYYY" 1>&2
-    exit 5
+    exit 6
 fi
 if [[ ! -r $YYYY ]]; then
     echo "$0: ERROR: arg is not a writable directory: $YYYY" 1>&2
-    exit 5
+    exit 6
 fi
 
 # verify that YYYY has a non-empty readable .year file
@@ -296,19 +295,19 @@ fi
 export YEAR_FILE="$YYYY/.year"
 if [[ ! -e $YEAR_FILE ]]; then
     echo  "$0: ERROR: YYYY/.year does not exist: $YEAR_FILE" 1>&2
-    exit 7
+    exit 6
 fi
 if [[ ! -f $YEAR_FILE ]]; then
     echo  "$0: ERROR: YYYY/.year is not a regular file: $YEAR_FILE" 1>&2
-    exit 7
+    exit 6
 fi
 if [[ ! -r $YEAR_FILE ]]; then
     echo  "$0: ERROR: YYYY/.year is not an readable file: $YEAR_FILE" 1>&2
-    exit 7
+    exit 6
 fi
 if [[ ! -s $YEAR_FILE ]]; then
     echo  "$0: ERROR: YYYY/.year is not a non-empty readable file: $YEAR_FILE" 1>&2
-    exit 7
+    exit 6
 fi
 
 # verify that YYYY/README.md is a non-empty readable file
@@ -316,19 +315,19 @@ fi
 export README_FILE="$YYYY/README.md"
 if [[ ! -e $README_FILE ]]; then
     echo "$0: ERROR: year $YYYY README.md does not exist: $README_FILE" 1>&2
-    exit 8
+    exit 6
 fi
 if [[ ! -f $README_FILE ]]; then
     echo "$0: ERROR: year $YYYY README.md is not a file: $README_FILE" 1>&2
-    exit 8
+    exit 6
 fi
 if [[ ! -r $README_FILE ]]; then
     echo "$0: ERROR: year $YYYY README.md is not a readable file: $README_FILE" 1>&2
-    exit 8
+    exit 6
 fi
 if [[ ! -s $README_FILE ]]; then
     echo "$0: ERROR: year $YYYY README.md is not a non-empty readable file: $README_FILE" 1>&2
-    exit 8
+    exit 6
 fi
 
 # verify that the md2html.sh is executable