The default first SCSI tape drive under Linux is /dev/st0. You can read more about tape drives naming convention used under Linux here.
# tar zcvf – /wwwdata | ssh [email protected] “cat > /backup/wwwdata.tar.gz”
php , date_default_timezone_set
Sets the default timezone used by all date/time functions in a script
date_default_timezone_set( “Asia/Taipei” );
useful mysql command
show status like ‘Qcache%’;
explain select …..
分析 schema
echo “select * from tbl_item procedure analyse()\G” | mysql db_name > ana.txt
mysql turning off query cache
set GLOBAL query_cache_size=0
adject file descriptors
On Unix, each TCP/IP connection uses a file descriptor, so you must increase the total number of descriptors available to the operating system, and also increase the maximum number of descriptors each process is allowed to use. All Unix style operating systems have a “ulimit” shell command (sh and bash) which can allow more open file descriptors to commands started in that shell, once the appropriate kernel tweak has been made. We recommend “ulimit -n 8192”. Here are our recommended kernel tweaks:
Linux: “echo 65536 > /proc/sys/fs/file-max” changes the number of system-wide file descriptors
FreeBSD: append to /etc/sysctl (or you can use sysctl -w to add these)
kern.maxfiles=65536
kern.maxfilesperproc=32768
Solaris: add the following to /etc/system and reboot:
set rlim_fd_max=0x8000
set rlim_fd_cur=0x8000