make log-once be script instead of function

[log-quiet] / log-once

diff --git a/log-once b/log-once
new file mode 100755 (executable)
index 0000000..f8938c8
--- /dev/null
+++ b/log-once
@@ -0,0 +1,102 @@
+#!/bin/bash
+# Copyright (C) 2016 Ian Kelling
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+append() {
+    cat >> "$1"
+}
+log-once() {
+    local help="Usage: log-once [OPTION]... LOG_NAME [LOG_MESSAGE]
+
+For cronjobs, email only once for repeated failures, and for success after failure.
+
+Meant for use in cronjobs where LOG_MESSAGE or STDIN represents an error,
+but we only want to output that to STDOUT if we've seen this type of
+error ERRORS(default 3) number of times in a row, then we don't
+want to output anything again until we've seen a success (an empty LOG_MESSAGE).
+
+Logs LOG_MESSAGE or STDIN to ~/.cron_errors/LOG_NAME, and keeps
+state in the same directory.
+
+-e ERRORS:  ERRORS is the number of errors to accumulate before outputing the error"
+    local cbase c c1 c2 log x i out file
+    errors=3
+    while true; do
+        if [[ $1 == --help ]]; then
+            echo "$help"
+            return
+        elif [[ $1 == -[0-9]* ]]; then
+            errors={$1#-}
+            shift
+        elif [[ $1 == -- ]]; then
+            shift
+            break
+        else
+            break
+        fi
+    done
+    log_name=$1
+    # todo, make option & make them overridable based on command line or env variable
+    cbase=$HOME/.cron-errors
+    [[ -d $cbase ]] || mkdir -p $cbase
+    c=$cbase/$log_name
+    # http://stackoverflow.com/questions/2456750/detect-presence-of-stdin-contents-in-shell-script
+    log=false
+    if [[ $2 ]]; then
+        log=true
+        # read stdin for anything which is not just a newline
+    elif [[ ! -t 0 ]]; then
+        while read -r x; do
+            output+=( $x )
+            [[ $x ]] && log=true
+        done
+    fi
+    if $log; then
+        file=
+        if [[ -f $c$((errors-1)) ]]; then
+            out="tee -a"
+        else
+            out=append
+        fi
+        for ((i=errors; i>=1; i--)); do
+            if [[ -f $c$((i-1)) ]]; then
+                file=$c$i
+                mv $c$((i-1)) $file
+                break
+            fi
+        done
+        if [[ ! $file ]]; then
+            if [[ -f $c$errors ]]; then
+                file=$c$errors
+            else
+                file=${c}1
+            fi
+        fi
+        $out $file <<<"log-once: $(date "+%A, %B %d, %r")"
+        if [[ $2 ]]; then
+            $out $file <<<"$2"
+        else
+            $out $file <<<"${output[@]}"
+            $out $file
+        fi
+        return 1
+    elif [[ -f $c$errors ]]; then
+        echo "log-once success after failure for $c"
+        rm -f $c$errors
+    else
+        rm -f $c[0-9]* # assuming  no one is putting crazy files names, as this is not exact
+    fi
+    return 0
+}
+log-once "$@"