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操作系统Interprocess Communication（IPC）实验源码。 在Unix的内核环境中

compile:
	gcc -o shmtool shmtool.c
run:
./shmtool w hello,world
Creating new shared memory segment
Done...

./shmtool w happy
Shared memory segment exisits-opening as client
Done...

ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x530760c3 9535490    root      666        100        0                       

./shmtool r
Shared memory segment exisits-opening as client
segptr:happy

./shmtool m 660
Shared memory segment exisits-opening as client
Old permissions were:666
New permissions are:660

ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x530760c3 9535490    root      660        100        0                       

./shmtool d
Shared memory segment exisits-opening as client
Shared memory segment marked for deletion

ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status