Question

While executing the “Client List” i get the below result,whats the meaning of the each flag

Slave
addr=100.0.0.0:0000 fd=5 idle=3 flags=S db=0 sub=0 psub=0 qbuf=0 obl=0 oll=0 events=r cmd=sync

Master
addr=100.0.0.0:0000 fd=6 idle=0 flags=N db=0 sub=0 psub=0 qbuf=0 obl=0 oll=0 events=r cmd=client

Answer 1

With client list, Redis prints one row per connected client.
From the redis.h and networking.c files of Redis source code:

• addr: address/port of the client
• fd: file descriptor corresponding to the socket
• idle: idle time of the connection in seconds
• flags: client flags (see below)
• db: current database ID
• sub: number of channel subscriptions
• psub: number of pattern matching subscriptions
• qbuf: query buffer length (0 means no query pending)
• obl: output buffer length
• oll: output list length (replies are queued in this list when the buffer is full)
• events: file descriptor events (see below)
• cmd: last command played

The client flags can be a combination of:

• O: the client is a slave in MONITOR mode
• S: the client is a normal slave server
• M: the client is a master
• x: the client is in a MULTI/EXEC context
• b: the client is waiting in a blocking operation
• i: the client is waiting for a VM I/O
• d: a watched keys has been modified – EXEC will fail
• c: connection to be closed after writing entire reply
• u: the client is unblocked
• N: no specific flag set

The file descriptor events can be:

• r: the client socket is readable (event loop)
• w: the client socket is writable (event loop)

It is my interpretation, please take it with a grain of salt.