PHP set MySQL socket location

I previously had the problem that my C applications where looking for a socket in /tmp/mysql.sock but my socket location had been set to /var/run/mysqld.sock. I now changed the settings in my.cnf to always put the socket into /tmp.

Now, when I try to run my web application using nginx and php5-fpm it does not find the socket because it still looks in /var/run/mysqld.sock. At first I created a link but then noted, that whenever I restart the machine, this link is deleted.

I searched through my php.ini and set all three (pdo_mysql.default_socket, mysql.default_socket, mysqli.default_socket) available socket options to /tmp/mysql.sock. I did this in the folder cgi, cli and fpm. However, it still does not work. Is there another option I need to add? Or should I rethink my approach in general?

Heres my php.ini:

   [PHP]

    engine = On
    short_open_tag = On
    asp_tags = Off
    precision = 14
    y2k_compliance = On
    output_buffering = 4096
    zlib.output_compression = Off
    implicit_flush = Off
    unserialize_callback_func =
    serialize_precision = 100
    allow_call_time_pass_reference = Off
    s    afe_mode = Off
    safe_mode_gid = Off
    safe_mode_include_dir =
    safe_mode_exec_dir =
    safe_mode_allowed_env_vars = PHP_
    safe_mode_protected_env_vars = LD_LIBRARY_PATH
    disable_functions =
    disable_classes =
    expose_php = On
    max_execution_time = 30
    max_input_time = 60
    memory_limit = 128M
    error_reporting = E_ALL & ~E_DEPRECATED
    display_errors = Off
    display_startup_errors = Off
    log_errors = On
    log_errors_max_len = 1024
    ignore_repeated_errors = Off
    ignore_repeated_source = Off
    report_memleaks = On
    track_errors = Off
    html_errors = Off
    variables_order = "GPCS"
    request_order = "GP"
    register_globals = Off
    register_long_arrays = Off
    register_argc_argv = Off
    auto_globals_jit = On
    post_max_size = 8M
    magic_quotes_gpc = Off
    magic_quotes_runtime = Off
    magic_quotes_sybase = Off
    auto_prepend_file =
    auto_append_file =
    default_mimetype = "text/html"
    doc_root =
    user_dir =
    enable_dl = Off
    file_uploads = On
    upload_max_filesize = 2M
    max_file_uploads = 20
    allow_url_fopen = On
    allow_url_include = Off
    default_socket_timeout = 60

    [Date]
    [filter]
    [iconv]
    [intl]
    [sqlite]
    [sqlite3]
    [Pcre]
    [Pdo]
    [Pdo_mysql]
    pdo_mysql.cache_size = 2000
    pdo_mysql.default_socket=/tmp/mysql.sock
    [Phar]
    [Syslog]
    define_syslog_variables  = Off
    [mail function]
    SMTP = localhost
        smtp_port = 25
    mail.add_x_header = On
    [SQL]
    sql.safe_mode = Off
    [ODBC]
    odbc.allow_persistent = On
    odbc.check_persistent = On
    odbc.max_persistent = -1
    odbc.max_links = -1
    odbc.defaultlrl = 4096
    odbc.defaultbinmode = 1
    [Interbase]
    ibase.allow_persistent = 1
    ibase.max_persistent = -1
    ibase.max_links = -1
    ibase.timestampformat = "%Y-%m-%d %H:%M:%S"
    ibase.dateformat = "%Y-%m-%d"
    ibase.timeformat = "%H:%M:%S"
    [MySQL]
    mysql.allow_local_infile = On
    mysql.allow_persistent = On
    mysql.cache_size = 2000
    mysql.max_persistent = -1
    mysql.max_links = -1
    mysql.default_port =
    mysql.default_socket=/tmp/mysql.sock
    mysql.default_host=
    mysql.default_user =
    mysql.default_password =
    mysql.connect_timeout = 60
    mysql.trace_mode = Off
    [MySQLi]
    mysqli.max_persistent = -1
    mysqli.allow_persistent = On
    mysqli.max_links = -1
    mysqli.cache_size = 2000
    mysqli.default_port = 3306
    mysqli.default_socket =/tmp/mysql.sock
    mysqli.default_host =
    mysqli.default_user =
    mysqli.default_pw =
    mysqli.reconnect = Off
    [mysqlnd]
    mysqlnd.collect_statistics = On
    mysqlnd.collect_memory_statistics = Off
    [OCI8]
    [PostgresSQL]
    pgsql.allow_persistent = On
    pgsql.auto_reset_persistent = Off
    pgsql.max_persistent = -1
    pgsql.max_links = -1
    pgsql.ignore_notice = 0
    pgsql.log_notice = 0
    [Sybase-CT]
    sybct.allow_persistent = On
    sybct.max_persistent = -1
    sybct.max_links = -1
    sybct.min_server_severity = 10
    sybct.min_client_severity = 10
    [bcmath]
    bcmath.scale = 0
    [browscap]
    [Session]
    session.save_handler = files
    session.use_cookies = 1
    session.use_only_cookies = 1
    session.name = PHPSESSID
    session.auto_start = 0
    session.cookie_lifetime = 0
    session.cookie_path = /
    session.cookie_domain =
    session.cookie_httponly =
    session.serialize_handler = php
    session.gc_probability = 1
    session.gc_divisor = 1000
    session.gc_maxlifetime = 1440
    session.bug_compat_42 = Off
    session.bug_compat_warn = Off
    session.referer_check =
    session.entropy_length = 0
    session.cache_limiter = nocache
    session.cache_expire = 180
    session.use_trans_sid = 0
    session.hash_function = 0
    session.hash_bits_per_character = 5
    url_rewriter.tags = "a=href,area=href,frame=src,input=src,form=fakeentry"
    [MSSQL]
    mssql.allow_persistent = On
    mssql.max_persistent = -1
    mssql.max_links = -1
    mssql.min_error_severity = 10
    mssql.min_message_severity = 10
    mssql.compatability_mode = Off
    mssql.secure_connection = Off
    [Assertion]
    [COM]
    [mbstring]
    [gd]
    [exif]
    [Tidy]
    tidy.clean_output = Off
    [soap]
    soap.wsdl_cache_enabled=1
    soap.wsdl_cache_dir="/tmp"
    soap.wsdl_cache_ttl=86400
    soap.wsdl_cache_limit = 5
    [sysvshm]
    [ldap]
    ldap.max_links = -1
    [mcrypt]

[dba]

Also, here's the nginx error.log:

PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2002] Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' in /var/www/php_includes/sfunctions.php:250

Here's how I currently access the db via PDO in PHP:

$db = new PDO('mysql:host=localhost;dbname=mydb', $dbUser, $dbPass);