nicer arg parsing

[chiark-utils.git] / scripts / expire-iso8601

diff --git a/scripts/expire-iso8601 b/scripts/expire-iso8601
index 082d33a75f61a74a8023a15bd03d50e69db214e6..7cb274e607991354cf88b890b108054c5c9ed9c7 100755 (executable)
--- a/scripts/expire-iso8601
+++ b/scripts/expire-iso8601
@@ -3,21 +3,23 @@ set -e
                        usage () {
                        cat <<END
 usage:
-  expire-iso8601 [<options>] <unit-in-seconds> <slop-in-seconds>
-     <min-interval-in-units> <number-to-keep>
-    [<min-interval-in-units> <number-to-keep> ...]
+  expire-iso8601 [<options>] <number>x<interval> [<number>x<interval> ...]
 options:
-   -n    do not really delete
-   -r    recursive removal (rm -r)
+   -u<unitlen>  <interval> is measured in units of <unitlen> seconds
+                   (default is 86400, so <interval> is in days)
+   -s<slop>     allow kept items to be <slop> seconds shorter apart than
+                   specified; default is 10% of <unitlen>
+   -n           do not really delete
+   -r           recursive removal (rm -r)
 example:
-   /home/ian/junk/expire-iso8601 86400 10000  1 14  7 4
-      uses units of 86400s (1 day) with a slop of 10ks;
+   /home/ian/junk/expire-iso8601 14x1 4x7
+      uses units of 86400s (1 day) with a slop of 8640
       it keeps 14 daily items
-       (that is 14 items, dated no less than 86400-10000s apart)
+       (that is 14 items, dated no less than 86400-8640 apart)
       and 7 weekly items
-       (that is 7 items, dated no less than 7*86400-10000s apart)
+       (that is 7 items, dated no less than 7*86400-8640 apart)
       the 14 daily and 7 weekly items may be the same, or not
-   There is no need to sort the list of interval/number pairs.
+   There is no need to sort the list of <number>x<interval> pairs.
 exit status:
    0                   ok
    4                   rm failed
@@ -31,7 +33,18 @@ badusage () { echo >&2 "bad usage: $*"; usage >&2; trap '' 0; exit 8; }
 
 #-------------------- argument parsing --------------------
 
+alldigits () {
+       [ "x${2##*[^0-9]}" = "x$2" ] || \
+               badusage "bad $1 \`$2'; must be all digits"
+       [ "$2" ] || badusage "bad $2; must be nonempty"
+       eval $1='$2'
+}
+
 rm=rm
+recurse=''
+unit=86400
+slop=''
+
 while [ $# -ge 1 ]; do
        arg=$1; shift
        case "$arg" in
@@ -39,9 +52,12 @@ while [ $# -ge 1 ]; do
        --help) usage; exit 0 ;;
        --*)    badusage "unknown option $arg" ;;
        -*)
+               val=${arg#-?}
                case "$arg" in
                -n*)    rm=: ;;
                -r*)    recurse=-r ;;
+               -u*)    alldigits unit "$val"; arg='' ;;
+               -s*)    alldigits slop "$val"; arg='' ;;
                *)      badusage "unknown option ${1:0:2}" ;;
                esac
                arg=-${arg#-?}
@@ -51,24 +67,13 @@ while [ $# -ge 1 ]; do
        esac
 done
 
-[ $# -ge 4 ] || badusage 'too few arguments'
-
-unit=$1
-slop=$2
-shift;shift
-
-[ $(($# % 2)) = 0 ] || badusage 'odd keep arguments (need min/extent pairs)'
-argl="$*"
-
-alldigits () {
-       [ "x${1##*[^0-9]}" = "x$1" ] || badusage "$2 must be all digits"
-       [ x$1 ] || badusage "$2 must be nonempty"
-}
+[ $# -ge 1 ] || badusage 'too few arguments'
+[ "$slop" ] || slop=$(( $unit / 10 ))
 
-while [ $# -gt 0 ]; do
-       min=$1; shift; extent=$1; shift
-       alldigits $min min
-       alldigits $extent extent
+for ni in "$@"; do
+       case "$ni" in *x*);; *) badusage "bad <number>x<interval> $ni";; esac
+       alldigits number "${ni%%x*}"
+       alldigits interval "${ni#*x}"
 done
 
 #-------------------- scanning the directory ----------
@@ -117,10 +122,9 @@ $l
 END
 )
 
-set $argl
-while [ $# != 0 ]; do
-       min=$(( $1 * $unit - $slop ))
-       wantcount=$2
+for ni in "$@"; do
+       min=$(( ${ni#*x} * $unit - $slop ))
+       wantcount=${ni%x*}
 
        ls=''
        lnew=''
@@ -129,7 +133,7 @@ while [ $# != 0 ]; do
                if [ $wantcount != 0 ]; then
                        if ! [ "$ls" ] || \
                           [ $(( $ls - $cs )) -ge $min ]; then
-                               echo "keep (for $1 $2) $cn"
+                               echo "keep (for $ni) $cn"
                                ls=$cs
                                ce=:$cs/$cn
                                wantcount=$(( $wantcount - 1 ))
@@ -138,9 +142,8 @@ while [ $# != 0 ]; do
                lnew="$lnew $ce"
        done
        if [ $wantcount != 0 ];then
-               echo "insufficient (for $1 $2) by $wantcount"
+               echo "insufficient (for $ni) by $wantcount"
        fi
-       shift;shift
        l=$lnew
 done
 
@@ -161,7 +164,7 @@ for ce in $l; do
        *)
                cn=${ce#*/}
                nonbroken_echo "expire $cn"
-               echo $rm $recurse -- $cn &
+               $rm $recurse -- $cn &
                jobs="$jobs $!"
                ;;
        esac