如何在PowerShell中实现识别截取后字符拼接，合并日志缩进行

需求说明 #

给定多行结构的系统日志，每条主日志行（行首无缩进）后跟随的若干行缩进附属内容，需要去除缩进附属内容的行首缩进和换行，直接拼接到所属主日志行的末尾。

输入示例 #

May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:
    ASL Module "com.apple.cdscheduler" claims selected messages.
    Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:
    ASL Module "com.apple.install" claims selected messages.
    Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:
    ASL Module "com.apple.callhistory.asl.conf" claims selected messages.
    Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:
    ASL Module "com.apple.authd" sharing output destination "/var/log/asl" with ASL Module "com.apple.asl".
    Output parameters from ASL Module "com.apple.asl" override any specified in ASL Module "com.apple.authd".
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:
    ASL Module "com.apple.mkb" sharing output destination "/private/var/log/keybagd.log" with ASL Module "com.apple.mkb.internal".
    Output parameters from ASL Module "com.apple.mkb.internal" override any specified in ASL Module "com.apple.mkb".

输出示例 #

May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:ASL Module "com.apple.cdscheduler" claims selected messages.Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:ASL Module "com.apple.install" claims selected messages.Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:ASL Module "com.apple.callhistory.asl.conf" claims selected messages.Those messages may not appear in standard system log files or in the ASL database.
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:ASL Module "com.apple.authd" sharing output destination "/var/log/asl" with ASL Module "com.apple.asl".Output parameters from ASL Module "com.apple.asl" override any specified in ASL Module "com.apple.authd".
May 13 00:30:00 BBAOMACBOOKAIR2 syslogd[113]: Configuration Notice:ASL Module "com.apple.mkb" sharing output destination "/private/var/log/keybagd.log" with ASL Module "com.apple.mkb.internal".Output parameters from ASL Module "com.apple.mkb.internal" override any specified in ASL Module "com.apple.mkb".

实现方案 #

可以直接使用awk命令完成转换，不需要额外安装工具：

awk '/^[^[:space:]]/ {if (NR>1) print buf; buf=$0; next} {sub(/^[[:space:]]+/,""); buf = buf $0} END {print buf}' 输入日志文件名.log > 输出日志文件名.log

命令逻辑说明 #

• 匹配行首无空白字符的主日志行：如果不是第一行，先输出上一条已经拼接完成的日志内容，再将当前行存入缓存变量buf，跳过后续逻辑
• 匹配行首带空白的缩进附属行：先删除行首所有空白字符，再将内容追加到缓存变量buf末尾
• 所有行处理完成后，输出最后一条缓存的拼接结果

内容的提问来源于stack exchange，提问作者Kevin