How to tail -f the latest log file with a given pattern

Question

I work with some log system which creates a log file every hour, like follows:

SoftwareLog.2010-08-01-08
SoftwareLog.2010-08-01-09
SoftwareLog.2010-08-01-10
         


        

Answer 1

#!/bin/bash

PATTERN="$1"

# Try to make sure sub-shells exit when we do.
trap "kill -9 -- -$BASHPID" SIGINT SIGTERM EXIT

PID=0
OLD_FILES=""
while true; do
  FILES="$(echo $PATTERN)"
  if test "$FILES" != "$OLD_FILES"; then
    if test "$PID" != "0"; then
      kill $PID
      PID=0
    fi
    if test "$FILES" != "$PATTERN" || test -f "$PATTERN"; then
      tail --pid=$$ -n 0 -F $PATTERN &
      PID=$!
    fi
  fi
  OLD_FILES="$FILES"
  sleep 1
done

Then run it as: tail.sh 'SoftwareLog*'

The script will lose some log lines if the logs are written to between checks. But at least it's a single script, with no symlinks required.