-noshell参数启动的erlang如何让standard_io支持unicode

2016-06-13

使用relx自动生成的启动脚本有foreground模式, 适合docker使用,
使用后发现docker logs里出来的日志有许多乱码...

查看脚本发现如下一行

1	FOREGROUNDOPTIONS="-noshell -noinput +Bd"

google搜索"noshell unicode", 在erlang文档里stdlib app的user guide中发现如下这段话:

io:setopts/{1,2} and the -oldshell/-noshell flags.
When Erlang is started with -oldshell or -noshell, the I/O-server for standard_io is default set to bytewise encoding, while an interactive shell defaults to what the environment variables says.

With the io:setopts/2 function you can set the encoding of a file or other I/O-server. This can also be set when opening a file. Setting the terminal (or other standard_io server) unconditionally to the option {encoding,utf8} will for example make UTF-8 encoded characters being written to the device regardless of how Erlang was started or the users environment.

Opening files with encoding option is convenient when writing or reading text files in a known encoding.

You can retrieve the encoding setting for an I/O-server using io:getopts().

找出error_logger的group_leader进程pid

1 2	> process_info(whereis(error_logger), group_leader). {group_leader,<0.615.0>}

发现是user进程

1 2	> process_info(pid(0,615,0), registered_name). {registered_name,user}

发现encoding为latin1

1 2	> io:getopts(user). [{binary,false},{encoding,latin1}]

设为unicode

> io:setopts(user, [{encoding, unicode}]).          
ok
> io:getopts(user).                       
[{binary,false},{encoding,unicode}]

解决!

参考链接

http://erlang.org/doc/apps/stdlib/unicode_usage.html
http://erlang.org/doc/man/user.html