Sort a group of log4j-based log files by timestamp

Assuming that each log file consists of complete timestamps on the beginning and end (i.e. it's not abruptly truncated), here's a quick command to list first and last timestamps of a set of log4j log files, sorted in ascending order by first timestamp:

$ (for i in *.log.out*; do echo -n $i'\t'$(sed '1p;$!d' $i | cut -d ' ' -f-2 | tr '\n' '\t')'\n'; done) | sort -k2

To sort by last timestamp on each file, change sort argument from -k2 to -k4

Example:

$ (for i in *.log.out*; do echo -n $i'\t'$(sed '1p;$!d' $i | cut -d ' ' -f-2 | tr '\n' '\t')'\n'; done) | sort -k2

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.30 2016-08-12 13:09:30,297 2016-08-12 13:53:27,785

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.29 2016-08-12 13:53:27,791 2016-08-12 16:02:24,046

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.28 2016-08-12 16:02:24,051 2016-08-12 16:13:18,553

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.27 2016-08-12 16:13:18,555 2016-08-12 16:40:21,115

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.26 2016-08-12 16:40:21,123 2016-08-12 17:26:27,145

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.25 2016-08-12 17:26:27,153 2016-08-12 17:27:35,976

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.24 2016-08-12 17:27:37,404 2016-08-12 17:56:26,459

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.23 2016-08-12 17:56:26,463 2016-08-12 18:25:09,816

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.22 2016-08-12 18:25:09,822 2016-08-12 19:10:34,036

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.21 2016-08-12 19:10:34,081 2016-08-12 19:44:30,899

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.20 2016-08-12 19:44:30,996 2016-08-12 20:01:21,222

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.19 2016-08-12 20:01:21,363 2016-08-12 21:23:20,933

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.18 2016-08-12 21:23:21,183 2016-08-12 23:14:29,238

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.17 2016-08-12 23:14:29,429 2016-08-13 00:47:05,370

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.16 2016-08-13 00:47:05,376 2016-08-13 01:01:45,803

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.15 2016-08-13 01:01:45,808 2016-08-13 02:23:24,499

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.14 2016-08-13 02:23:24,499 2016-08-13 09:41:18,893

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.13 2016-08-13 09:41:18,898 2016-08-13 11:05:50,145

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.12 2016-08-13 11:05:50,149 2016-08-13 11:58:56,914

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.11 2016-08-13 11:58:56,919 2016-08-13 13:58:17,794

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.10 2016-08-13 13:58:17,800 2016-08-13 15:55:48,996

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.9 2016-08-13 15:55:49,001 2016-08-13 17:05:04,935

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.8 2016-08-13 17:05:04,939 2016-08-13 17:58:42,547

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.7 2016-08-13 17:58:42,552 2016-08-13 18:13:34,622

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.6 2016-08-13 18:13:34,627 2016-08-13 19:41:18,039

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.5 2016-08-13 19:41:18,045 2016-08-13 21:13:34,207

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.4 2016-08-13 21:13:34,209 2016-08-13 23:13:13,734

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.3 2016-08-13 23:13:13,737 2016-08-14 00:04:13,013

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.2 2016-08-14 00:04:13,017 2016-08-14 00:58:07,933

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out.1 2016-08-14 00:58:07,937 2016-08-14 01:43:06,945

hadoop-cmf-hdfs2-NAMENODE-namenode01.company.com.log.out 2016-08-14 01:43:07,107 2016-08-14 01:56:02,070