ラッパーも含めて mysqldが起動するときにどのmy.cnfを舐めてるのか知りたいとき

いやまあ、マニュアルに書いてあるけど。
http://dev.mysql.com/doc/refman/5.6/en/option-files.html

Linuxで公式MySQL、--defaults-file, --defaults-extra-fileを指定しない場合は、

• /etc/my.cnf
• /etc/mysql/my.cnf
• /usr/local/mysql/etc/my.cnf
• SYSCONFDIR/my.cnfのこと。
• 公式のバイナリーはSYSCONFDIR== /usr/local/mysql/etc。cmakeのオプションで変えられる。
• MariaDBはこいつが設定されていないっぽい。
• /usr/local/mysql/my.cnf
• $MYSQL_HOME/my.cnfのこと。
• basedirを設定してれば$MYSQL_HOME== basedirになる。
• /home/mysql/.my.cnf
• $HOME/.my.cnfのこと。コイツだけドットファイル。

の順番で読む。
とはいえこんなのめんどくさくて憶えてられなかったり、SYSCONFDIRやMYSQL_HOMEが思いもしない変なところになってたりすることがあったりなかったりするかも知れないので、調べ方だけメモってみる。

# strace -ff -e open -e stat /usr/mysql/5.5.34/bin/mysqld_multi start 55,56 2>&1 | grep "my\.cnf"

[pid  7359] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  7359] stat("/etc/mysql/my.cnf", 0x7fffa1322e40) = -1 ENOENT (No such file or directory)
[pid  7359] stat("/usr/local/mysql/etc/my.cnf", 0x7fffa1322e40) = -1 ENOENT (No such file or directory)
[pid  7359] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
stat("/etc/mysql/my.cnf", 0x1739130)    = -1 ENOENT (No such file or directory)
stat("/usr/mysql/5.5.34/my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
stat("/usr/mysql/5.5.34/my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7361] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  7361] stat("/etc/mysql/my.cnf", 0x7fffdaeb46e0) = -1 ENOENT (No such file or directory)
[pid  7361] stat("/usr/local/mysql/etc/my.cnf", 0x7fffdaeb46e0) = -1 ENOENT (No such file or directory)
[pid  7361] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7365] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  7365] stat("/etc/mysql/my.cnf", 0x7fff4038abf0) = -1 ENOENT (No such file or directory)
[pid  7365] stat("/usr/local/mysql/etc/my.cnf", 0x7fff4038abf0) = -1 ENOENT (No such file or directory)
[pid  7365] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7371] stat("/usr/mysql/5.6.14/data/my.cnf", 0x7fff0d4bc2b0) = -1 ENOENT (No such file or directory)
[pid  7371] stat("/usr/mysql/5.6.14/my.cnf", 0x7fff0d4bc2c0) = -1 ENOENT (No such file or directory)
[pid  7371] stat("/usr/mysql/5.6.14/data/my.cnf", 0x7fff0d4bc320) = -1 ENOENT (No such file or directory)
[pid  7407] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  7407] stat("/etc/mysql/my.cnf", 0x7fff380ae700) = -1 ENOENT (No such file or directory)
[pid  7407] stat("/usr/local/mysql/etc/my.cnf", 0x7fff380ae700) = -1 ENOENT (No such file or directory)
[pid  7407] stat("/usr/mysql/5.6.14/my.cnf", 0x7fff380ae700) = -1 ENOENT (No such file or directory)
[pid  7407] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7364] stat("/usr/mysql/5.5.34/data/my.cnf", 0x7fffb0b1a980) = -1 ENOENT (No such file or directory)
[pid  7364] stat("/usr/mysql/5.5.34/my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7364] stat("/usr/mysql/5.5.34/data/my.cnf", 0x7fffb0b1a990) = -1 ENOENT (No such file or directory)
[pid  7364] stat("/usr/mysql/5.5.34/data/my.cnf", 0x7fffb0b1a9f0) = -1 ENOENT (No such file or directory)
[pid  7421] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  7421] stat("/etc/mysql/my.cnf", 0x7fffde0a77e0) = -1 ENOENT (No such file or directory)
[pid  7421] stat("/usr/local/mysql/etc/my.cnf", 0x7fffde0a77e0) = -1 ENOENT (No such file or directory)
[pid  7421] stat("/usr/mysql/5.5.34/my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  7421] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  8339] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  8339] stat("/etc/mysql/my.cnf", 0x7fff59e821d0) = -1 ENOENT (No such file or directory)
[pid  8339] stat("/usr/local/mysql/etc/my.cnf", 0x7fff59e821d0) = -1 ENOENT (No such file or directory)
[pid  8339] stat("/usr/mysql/5.6.14/my.cnf", 0x7fff59e821d0) = -1 ENOENT (No such file or directory)
[pid  8339] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  8416] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=3584, ...}) = 0
[pid  8416] stat("/etc/mysql/my.cnf", 0x7fffc5f4d310) = -1 ENOENT (No such file or directory)
[pid  8416] stat("/usr/local/mysql/etc/my.cnf", 0x7fffc5f4d310) = -1 ENOENT (No such file or directory)
[pid  8416] stat("/usr/mysql/5.5.34/my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
[pid  8416] stat("/root/.my.cnf", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0

実際どれを開いたかだけでよければ、"-e stat"はイラナイ。
小ネタ、小ネタ。


【2015/02/18 19:39】
mysqldの読むやつ見たいんだったらmysqld --help --verboseでいいじゃん？ って何度か言われてたので追記。
mysqld --help --verboseだと、my.cnfに設定したbasedirの値が読み取られる前にパスが解釈されるので、MYSQL_HOME/my.cnfが表示されない。

$ /usr/mysql/5.6.23/bin/mysqld --help --verbose  | grep cnf
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf
                      my.cnf, $MYSQL_TCP_PORT, /etc/services, built-in default
2015-02-19 19:35:47 29891 [Note] Binlog end
2015-02-19 19:35:47 29891 [Note] Shutting down plugin 'CSV'
2015-02-19 19:35:47 29891 [Note] Shutting down plugin 'MyISAM'

$ strace -f -e stat /usr/mysql/5.6.23/bin/mysqld 2>&1 | grep my\.cnf
stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=4456, ...}) = 0
stat("/etc/mysql/my.cnf", 0x7fffd4f430d0) = -1 ENOENT (No such file or directory)
stat("/usr/local/mysql/etc/my.cnf", 0x7fffd4f430d0) = -1 ENOENT (No such file or directory)
stat("/home/yoku0825/.my.cnf", 0x7fffd4f430d0) = -1 ENOENT (No such file or directory)


$ strace -f -e stat /usr/mysql/5.6.23/bin/mysqld_safe 2>&1 | grep my\.cnf
stat("/usr/mysql/5.6.23/data/my.cnf", 0x7fff56f127f0) = -1 ENOENT (No such file or directory)
stat("/usr/mysql/5.6.23/my.cnf", {st_mode=S_IFREG|0664, st_size=943, ...}) = 0
stat("/usr/mysql/5.6.23/data/my.cnf", 0x7fff56f12800) = -1 ENOENT (No such file or directory)
stat("/usr/mysql/5.6.23/data/my.cnf", 0x7fff56f12860) = -1 ENOENT (No such file or directory)
[pid 28434] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=4456, ...}) = 0
[pid 28434] stat("/etc/mysql/my.cnf", 0x7ffffdd236c0) = -1 ENOENT (No such file or directory)
[pid 28434] stat("/usr/local/mysql/etc/my.cnf", 0x7ffffdd236c0) = -1 ENOENT (No such file or directory)
[pid 28434] stat("/usr/mysql/5.6.23/my.cnf", {st_mode=S_IFREG|0664, st_size=943, ...}) = 0
[pid 28434] stat("/home/yoku0825/.my.cnf", 0x7ffffdd236c0) = -1 ENOENT (No such file or directory)
[pid 28916] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=4456, ...}) = 0
[pid 28916] stat("/etc/mysql/my.cnf", 0x7fff43cc1bd0) = -1 ENOENT (No such file or directory)
[pid 28916] stat("/usr/local/mysql/etc/my.cnf", 0x7fff43cc1bd0) = -1 ENOENT (No such file or directory)
[pid 28916] stat("/usr/mysql/5.6.23/my.cnf", {st_mode=S_IFREG|0664, st_size=943, ...}) = 0
[pid 28916] stat("/home/yoku0825/.my.cnf", 0x7fff43cc1bd0) = -1 ENOENT (No such file or directory)
[pid 29004] stat("/etc/my.cnf", {st_mode=S_IFREG|0644, st_size=4456, ...}) = 0
[pid 29004] stat("/etc/mysql/my.cnf", 0x7fff76cacf80) = -1 ENOENT (No such file or directory)
[pid 29004] stat("/usr/local/mysql/etc/my.cnf", 0x7fff76cacf80) = -1 ENOENT (No such file or directory)
[pid 29004] stat("/usr/mysql/5.6.23/my.cnf", {st_mode=S_IFREG|0664, st_size=943, ...}) = 0
[pid 29004] stat("/home/yoku0825/.my.cnf", 0x7fff76cacf80) = -1 ENOENT (No such file or directory)

よく憶えてないんだけど、たぶんこれがラッパーに隠蔽されて(mysql.serverが中でゴニョゴニョやってるとかそんなの)るのが嫌でstraceで取ったんじゃないかなぁと思う。

$ MYSQL_HOME=/usr/mysql/5.6.23 /usr/mysql/5.6.23/bin/mysqld --help --verbose  | grep cnf
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf /usr/mysql/5.6.23/my.cnf ~/.my.cnf
                      my.cnf, $MYSQL_TCP_PORT, /etc/services, built-in default
2015-02-19 19:35:18 29889 [Note] Binlog end
2015-02-19 19:35:18 29889 [Note] Shutting down plugin 'CSV'
2015-02-19 19:35:18 29889 [Note] Shutting down plugin 'MyISAM'

$MYSQL_HOMEをちゃんと環境変数で与えておけば、mysqld --help --verboseでも見える。

あとはmy.cnfに!include が書いてあるケースとかも--help --verboseでは拾えないなぁとかそんなことをぼんやりと。