Updating variables in my.cnf

Question

I set lower_case_table_names = 2 in /etc/my.cnf file. I also updated this variable in /etc/mysql/my.cnf file. After setting the variable I restarted mysql server, but still the value is 0, when I use SHOW VARIABLES.

I'm using MySQL 5.5. Any Ideas what else needs to be done?

UPDATE

my.cnf content:-

#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
# 
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
lower_case_table_names = 2
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking

#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
bind-address        = 127.0.0.1
#
# * Fine Tuning
#
key_buffer      = 16M
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit   = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#log_slow_queries   = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id      = 1
#log_bin            = /var/log/mysql/mysql-bin.log
expire_logs_days    = 10
max_binlog_size         = 100M
#binlog_do_db       = include_database_name
#binlog_ignore_db   = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem



[mysqldump]
quick
quote-names
max_allowed_packet  = 16M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completition

[isamchk]
key_buffer      = 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/

Answer 1

As you can see in the file there are multiple places where config files are also loaded.

!includedir /etc/mysql/conf.d/: Check every file in this directory if the setting is overwritten by one:

grep -i lower_case_table_names /etc/mysql/conf.d/*

or check the files manually and search for the config value.

# - "~/.my.cnf" to set user-specific options.: Check the .my.cnf of the user that runs the mysql daemon, maybe there is this setting overwritten.

Find out the uid of the user with:

ps -ef | grep mysql

The first row is the uid. Find the user's home directory with:

grep <uid> /etc/passwd

the 6th :-separated string is the home directory. When in this directory is a .my.cnf, this file is loaded.

Stop the mysql daemon with /etc/init.d/mysql stop. And check if the daemon is stopped with pgrep mysql and pgrep mysqld. If the pgrep commands still return pids then kill those pids with kill. Sometimes mysql needs a very long time to stop with huge databases, thats normal. So first wait before killing things.

If you are sure mysql is stopped and all config files are cleaned from this config value, then start mysql again with /etc/init.d/mysql start and check the value.

Answer 2

For those using Windows with the Workbench 6.1, here's how I found to make this work. Select your schema and in the query box, enter: set global max_allowed_packet = 1073741824. You can use a lower number, but it must be a multiple of 1024. This is the largest value allowed (1 gig). Once you do this, SHOW VARIABLES doesn't show the change :(, but apparently, it does change. Immediately (may not be necessary) after executing the above statement, go to Server/Import. The error "... 9932: MySQL server has gone away" no longer comes up.