Endless logcat on device (no terminal) with log rotation and convenience commands.

endless-logcat.sh

#!/usr/bin/env bash

set -e

case $1 in
help)
  cat << EOF
Capture logcat endlessly inside the device.
This should be ran on a computer that is connected to an android device using adb.
Commands:
  status  - show capture and stored logs status
  start   - start capturing logs. previous instance will be stopped
  stop    - stop capturing logs
  pull    - copy all capture log files to this computer
  clean   - remove all captured log files from the device
  help    - this message
EOF
  ;;
clean)
  echo "Cleaning all existing log files in /sdcard/logcat/*"
  adb shell rm -fr /sdcard/logcat/
  ;;

start)
  echo "Starting log capture in the background in /sdcard/logcat/logcat.log*
use the status command for more info:
   $0 status"

adb shell <<EOF
  kill -9 \$(cat /sdcard/logcat-capture.pid 2>/dev/null) 2>/dev/null
  mkdir -p /sdcard/logcat
  nohup logcat -f /sdcard/logcat/logcat.log -r 20000 -n 10 '*:D' >/dev/null 2>&1 &
  echo "\${!}" > /sdcard/logcat-capture.pid
EOF
  ;;

stop)
adb shell <<EOF
  if [ "\$(cat /sdcard/logcat-capture.pid 2>/dev/null || echo '')" ]; then
    echo "Found running capture - stopping"
    kill "\$(cat /sdcard/logcat-capture.pid 2>/dev/null || echo '')"
  else
    echo "No running capture was found"
  fi
  rm -fr /sdcard/logcat-capture.pid
EOF
  ;;

pull)
  echo "Pulling log files to current dir /sdcard/logcat/ -> ./logcat"
  adb pull "/sdcard/logcat/"
  ;;

status)
adb shell <<EOF
  if [ "\$(kill -0 "\$(cat /sdcard/logcat-capture.pid 2>/dev/null)" 2>/dev/null && echo "1" || echo "")" ]; then
    echo "Job is running  pid:\$(cat /sdcard/logcat-capture.pid)"
  else
    echo "No running job was found"
  fi

  echo "List of stored log files in '/sdcard/logcat/*':"
  ls -lh /sdcard/logcat/* | grep 'logcat.log' | awk '{ print "  "\$6" "\$7"  "\$5"  "\$8 }'
EOF
  ;;
esac

echo "Done"