logger 命令用于在系统日志或者系统日志中记录消息。
我们可以在命令行上记录消息字符串或者提供一个文件作为输入，其中可以包含要记录的消息。

查看 logger 命令的可用开关：

# logger --help
Usage:
 logger [options] [message]
Options:
 -T, --tcp             use TCP only
 -d, --udp             use UDP only
 -i, --id              log the process ID too
 -f, --file [file]     log the contents of this file
 -h, --help            display this help text and exit
 -S, --size [num]      maximum size for a single message (default 1024)
 -n, --server [name]   write to this remote syslog server
 -P, --port [port]     use this port for UDP or TCP connection
 -p, --priority [prio] mark given message with this priority
 -s, --stderr          output message to standard error as well
 -t, --tag [tag]       mark every line with this tag
 -u, --socket [socket] write to this Unix socket
 -V, --version         output version information and exit

记录器命令示例

1. 将消息记录到标准错误和系统日志中

# logger -s "This is a test message"

2. 将消息记录到指定文件

# logger -f file "This is a test message"

3. 记录指定优先级的消息

# logger -p 1 "This is a test message"

4. 用指定的标签标记每一行

# logger -t TAG "This is a test message"

5. 允许消息以连字符开头

# logger -- "This is a test message"