环境

ubuntu 20.04

memcached安装

sudo apt install memcached

启动，重启，状态

service memcached status
service memcached start
service memcached restart

终端连接和退出

telnet 127.0.0.1 11211

quit

set 命令 语法

set key flags exptime bytes [noreply] 
value 

参数

key：键值 key-value 结构中的 key，用于查找缓存值。
flags：可以包括键值对的整型参数，客户机使用它存储关于键值对的额外信息 。
exptime：在缓存中保存键值对的时间长度（以秒为单位，0 表示永远）
bytes：在缓存中存储的字节数
noreply（可选）： 该参数告知服务器不需要返回数据
value：存储的值（始终位于第二行）（可直接理解为key-value结构中的value）

实例

set name 0 300 10
huyongjian
STORED
get name
VALUE name 0 10
huyongjian
END

add 命令

add key1 0 300 6
value1
STORED
get key1
VALUE key1 0 6
value1
END

replace 命令

replace key1 0 300 8
value111
STORED
get key1
VALUE key1 0 8
value111
END

append 命令

append key1 0 300 10
huyongjian
STORED
get key1
VALUE key1 0 18
value111huyongjian
END

prepend 命令

prepend key1 0 300 4
name
STORED
get key1
VALUE key1 0 22
namevalue111huyongjian
END

get 命令

get key1

get key1 key2

gets 命令

gets key

delete 命令

delete key [noreply]

delete key1
DELETED

incr 命令

语法

incr key increment_value

set key1 0 900 1
1
STORED
incr key1 5
6
get key1
VALUE key1 0 1
6
END

decr 命令

语法

decr key decrement_value

get key1
VALUE key1 0 1
6
END
decr key1 3
3

stats 命令

stats
STAT pid 1848611
STAT uptime 2291
STAT time 1626806924
STAT version 1.5.22
STAT libevent 2.1.11-stable
STAT pointer_size 64
STAT rusage_user 0.170337
STAT rusage_system 0.208419
STAT max_connections 1024
STAT curr_connections 1
STAT total_connections 4
STAT rejected_connections 3
STAT connection_structures 2
STAT reserved_fds 20
STAT cmd_get 16
STAT cmd_set 11
STAT cmd_flush 0
STAT cmd_touch 0
STAT cmd_meta 0
STAT get_hits 13
STAT get_misses 3
STAT get_expired 1
STAT get_flushed 0
STAT delete_misses 0
STAT delete_hits 1
STAT incr_misses 0
STAT incr_hits 1
STAT decr_misses 0
STAT decr_hits 1
STAT cas_misses 0
STAT cas_hits 0
STAT cas_badval 0
STAT touch_hits 0
STAT touch_misses 0
STAT auth_cmds 0
STAT auth_errors 0
STAT bytes_read 631
STAT bytes_written 722
STAT limit_maxbytes 67108864
STAT accepting_conns 1
STAT listen_disabled_num 0
STAT time_in_listen_disabled_us 0
STAT threads 4
STAT conn_yields 0
STAT hash_power_level 16
STAT hash_bytes 524288
STAT hash_is_expanding 0
STAT slab_reassign_rescues 0
STAT slab_reassign_chunk_rescues 0
STAT slab_reassign_evictions_nomem 0
STAT slab_reassign_inline_reclaim 0
STAT slab_reassign_busy_items 0
STAT slab_reassign_busy_deletes 0
STAT slab_reassign_running 0
STAT slabs_moved 0
STAT lru_crawler_running 0
STAT lru_crawler_starts 2295
STAT lru_maintainer_juggles 4257
STAT malloc_fails 0
STAT log_worker_dropped 0
STAT log_worker_written 0
STAT log_watcher_skipped 0
STAT log_watcher_sent 0
STAT bytes 129
STAT curr_items 2
STAT total_items 8
STAT slab_global_page_pool 0
STAT expired_unfetched 0
STAT evicted_unfetched 0
STAT evicted_active 0
STAT evictions 0
STAT reclaimed 0
STAT crawler_reclaimed 1
STAT crawler_items_checked 9
STAT lrutail_reflocked 0
STAT moves_to_cold 13
STAT moves_to_warm 5
STAT moves_within_lru 0
STAT direct_reclaims 0
STAT lru_bumps_dropped 0
END

pid： memcache服务器进程ID
uptime：服务器已运行秒数
time：服务器当前Unix时间戳
version：memcache版本
pointer_size：操作系统指针大小
rusage_user：进程累计用户时间
rusage_system：进程累计系统时间
curr_connections：当前连接数量
total_connections：Memcached运行以来连接总数
connection_structures：Memcached分配的连接结构数量
cmd_get：get命令请求次数
cmd_set：set命令请求次数
cmd_flush：flush命令请求次数
get_hits：get命令命中次数
get_misses：get命令未命中次数
delete_misses：delete命令未命中次数
delete_hits：delete命令命中次数
incr_misses：incr命令未命中次数
incr_hits：incr命令命中次数
decr_misses：decr命令未命中次数
decr_hits：decr命令命中次数
cas_misses：cas命令未命中次数
cas_hits：cas命令命中次数
cas_badval：使用擦拭次数
auth_cmds：认证命令处理的次数
auth_errors：认证失败数目
bytes_read：读取总字节数
bytes_written：发送总字节数
limit_maxbytes：分配的内存总大小（字节）
accepting_conns：服务器是否达到过最大连接（0/1）
listen_disabled_num：失效的监听数
threads：当前线程数
conn_yields：连接操作主动放弃数目
bytes：当前存储占用的字节数
curr_items：当前存储的数据总数
total_items：启动以来存储的数据总数
evictions：LRU释放的对象数目
reclaimed：已过期的数据条目来存储新数据的数目

stats items 命令

stats items
STAT items:1:number 2
STAT items:1:number_hot 0
STAT items:1:number_warm 0
STAT items:1:number_cold 2
STAT items:1:age_hot 0
STAT items:1:age_warm 0
STAT items:1:age 1455
STAT items:1:mem_requested 129
STAT items:1:evicted 0
STAT items:1:evicted_nonzero 0
STAT items:1:evicted_time 0
STAT items:1:outofmemory 0
STAT items:1:tailrepairs 0
STAT items:1:reclaimed 0
STAT items:1:expired_unfetched 0
STAT items:1:evicted_unfetched 0
STAT items:1:evicted_active 0
STAT items:1:crawler_reclaimed 1
STAT items:1:crawler_items_checked 11
STAT items:1:lrutail_reflocked 0
STAT items:1:moves_to_cold 13
STAT items:1:moves_to_warm 5
STAT items:1:moves_within_lru 0
STAT items:1:direct_reclaims 0
STAT items:1:hits_to_hot 0
STAT items:1:hits_to_warm 0
STAT items:1:hits_to_cold 13
STAT items:1:hits_to_temp 0
END

stats slabs 命令

stats slabs
STAT 1:chunk_size 96
STAT 1:chunks_per_page 10922
STAT 1:total_pages 1
STAT 1:total_chunks 10922
STAT 1:used_chunks 2
STAT 1:free_chunks 10920
STAT 1:free_chunks_end 0
STAT 1:get_hits 13
STAT 1:cmd_set 11
STAT 1:delete_hits 1
STAT 1:incr_hits 1
STAT 1:decr_hits 1
STAT 1:cas_hits 0
STAT 1:cas_badval 0
STAT 1:touch_hits 0
STAT active_slabs 1
STAT total_malloced 1048576
END

stats sizes 命令

stats sizes
STAT 96 1
END

flush_all 命令

get key1
VALUE key1 0 1
3
END
flush_all
OK
get key1
END