user-tools/partial

   1 #!/bin/bash
   2
   3 true <<EOF
   4 =pod
   5
   6 =head1 NAME
   7
   8 partial - Show an earlier started long-running command's partial output
   9
  10 =head1 SYNOPSIS
  11
  12 partial [--restart|--forget|--wait|--pid] <B<COMMAND>> [<B<ARGUMENTS>>]
  13
  14 =head1 DESCRIPTION
  15
  16 On first invocation partial(1) starts B<COMMAND> in the background.
  17 On subsequent invocations, it prints the command's output to stdout which is
  18 generated so far, including the parts which are shown before too,
  19 and keep it running in the background.
  20 Hence the name 'partial', because it shows a command's partial output.
  21 When the command finished, partial(1) prints the whole output
  22 and exits with B<COMMAND>'s exit code.
  23
  24 =head1 OPTIONS
  25
  26 =over 4
  27
  28 =item -f, --forget
  29
  30 Terminate (SIGTERM) previous instance of the same command
  31 and clean up status directory, even if it's running.
  32
  33 =item -r, --restart
  34
  35 Terminate command if running (like with --forget) and start it again.
  36
  37 =item -w, --wait
  38
  39 On first run, wait for the complete output.
  40
  41 =item -p, --pid
  42
  43 display PID
  44
  45 =item -q, --quiet
  46
  47 less verbose
  48
  49 =back
  50
  51 =head1 STATUS CODES
  52
  53 =over 4
  54
  55 =item B<115>
  56
  57 command started
  58
  59 =item B<114>
  60
  61 partial output shown
  62
  63 =item I<nnn>
  64
  65 called command returned with this status code I<nnn>
  66
  67 =back
  68
  69 =head1 LIMITS
  70
  71 If B<COMMAND> does not exit normally, but gets terminated by a signal,
  72 the exit code is indistinguishable from a normal exit's status code,
  73 due to bash(1) uses the value of 128+B<N> as the exit status
  74 when a command terminates on a fatal signal B<N>.
  75
  76 =cut
  77
  78 EOF
  79
  80
  81 set -e
  82 set -o pipefail
  83 set -u
  84
  85 print_partial()
  86 {
  87         cat "$dir/stdout"
  88 }
  89
  90 warnx()
  91 {
  92         echo "${0##*/}: $*" >&2
  93 }
  94
  95 verbose()
  96 {
  97         if [ $opt_quiet = no ]
  98         then
  99                 "$@"
 100         fi
 101 }
 102
 103 help()
 104 {
 105         pod2text "$0"
 106 }
 107
 108 remove()
 109 {
 110         [ ! -e "$1" ] || command remove "$1"
 111 }
 112
 113 opt_restart=no
 114 opt_forget=no
 115 opt_wait=no
 116 opt_pid=no
 117 opt_quiet=no
 118
 119 while [ $# -gt 0 ]
 120 do
 121         case "${1:-}" in
 122         --restart|-r)
 123                 opt_restart=yes
 124                 opt_forget=yes
 125                 ;;
 126         --forget|-f)
 127                 opt_forget=yes
 128                 ;;
 129         --wait|-w)
 130                 opt_wait=yes
 131                 ;;
 132         --pid|-p)
 133                 opt_pid=yes
 134                 ;;
 135         --quiet|-q)
 136                 opt_quiet=yes
 137                 ;;
 138         --help)
 139                 help
 140                 exit 0
 141                 ;;
 142         --)
 143                 shift
 144                 break
 145                 ;;
 146         -*)
 147                 warnx "unknown option: $1"
 148                 exit -1
 149                 ;;
 150         *)
 151                 break
 152                 ;;
 153         esac
 154         shift
 155 done
 156
 157 if [ $# = 0 ]
 158 then
 159         help
 160         exit -1
 161 fi
 162
 163 declare -a command=("$@")
 164 command_str=${command[*]}
 165 commandhash=`echo "$command_str" | sha256sum | cut -f1 -d' '`
 166
 167 dir=~/.cache/partial/$commandhash
 168
 169 if [ $opt_pid = yes ]
 170 then
 171         cat "$dir/pid"
 172         exit
 173 fi
 174
 175 if [ $opt_forget = yes ]
 176 then
 177         if [ -d "$dir" ]
 178         then
 179                 pid=`cat "$dir/pid" 2>/dev/null || true`
 180                 if [ -n "$pid" ]
 181                 then
 182                         while kill -0 "$pid"
 183                         do
 184                                 kill "$pid"
 185                                 sleep 0.2
 186                         done
 187                 fi
 188                 remove "$dir/pid"
 189                 remove "$dir/lock"
 190                 remove "$dir/stdout"
 191                 remove "$dir/running.lock"
 192                 remove "$dir/status"
 193                 remove "$dir/command.txt"
 194                 remove "$dir"
 195         fi
 196
 197         if [ $opt_restart = no ]
 198         then
 199                 exit
 200         fi
 201 fi
 202
 203 mkdir -p "$dir"
 204
 205 exec {lockfd}>>"$dir/lock"
 206 flock -x $lockfd
 207
 208 exec {runlockfd}>>"$dir/running.lock"
 209 verbose warnx "state in $dir"
 210
 211 if flock -n -x $runlockfd
 212 then
 213         if [ -e "$dir/status" ]
 214         then
 215                 verbose warnx "command finished: $(stat -c %y "$dir/status")"
 216                 print_partial
 217                 status=`cat "$dir/status"`
 218                 exit $status
 219         else
 220                 echo "$command_str" > "$dir/command.txt"
 221
 222                 if [ $opt_wait = yes ]
 223                 then
 224                         set +e
 225                         command "${command[@]}" | tee "$dir/stdout"
 226                         status=${PIPESTATUS[0]}
 227                         echo -n $status >"$dir/status"
 228
 229                         exit $status
 230                 else
 231                         (
 232                                 flock -u $lockfd
 233                                 set +e
 234                                 command "${command[@]}" > "$dir/stdout"
 235                                 echo -n $? >"$dir/status"
 236                         ) &
 237
 238                         echo $! > "$dir/pid"
 239                         verbose warnx "command started"
 240
 241                         exit 115
 242                 fi
 243         fi
 244 else
 245         flock -u $runlockfd
 246
 247         verbose warnx "command is in progress since $(stat -c %y "$dir/command.txt"), partial output follows."
 248         print_partial
 249         exit 114
 250 fi