SEGBRK(2) System Calls Manual SEGBRK(2)NAME
segbrk - change memory allocation
int segbrk(void *saddr, void *addr)
Segbrk sets the system's idea of the lowest unused location of a segment to addr rounded up to the next multiple of a page size, typically
4096 bytes. The segment is identified by saddr which may be any valid address within the segment.
A call to segbrk with a zero addr argument returns the address of the top of bss.
The system will prevent segments from overlapping and will not allow the length of the text, data, or stack segment to be altered.
SEE ALSO brk(2), segattach(2), segflush(2)
Check Out this Related Man Page
SHMAT(2) BSD System Calls Manual SHMAT(2)NAME
shmat, shmdt -- attach or detach shared memory
Standard C Library (libc, -lc)
shmat(int shmid, const void *addr, int flag);
shmdt(const void *addr);
The shmat() system call attaches the shared memory segment identified by shmid to the calling process's address space. The address where the
segment is attached is determined as follows:
o If addr is 0, the segment is attached at an address selected by the kernel.
o If addr is nonzero and SHM_RND is not specified in flag, the segment is attached the specified address.
o If addr is specified and SHM_RND is specified, addr is rounded down to the nearest multiple of SHMLBA.
The shmdt() system call detaches the shared memory segment at the address specified by addr from the calling process's address space.
Upon success, shmat() returns the address where the segment is attached; otherwise, -1 is returned and errno is set to indicate the error.
The shmdt() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate
The shmat() system call will fail if:
[EINVAL] No shared memory segment was found corresponding to shmid.
[EINVAL] The addr argument was not an acceptable address.
The shmdt() system call will fail if:
[EINVAL] The addr argument does not point to a shared memory segment.
SEE ALSO shmctl(2), shmget(2)BSD August 2, 1995 BSD
What is the point of this? Whenever I close my shell it appends to the history file without adding this. I have never seen it overwrite my history file.
# When the shell exits, append to the history file instead of overwriting it
shopt -s histappend (3 Replies)