Using "strace" to see the Sys. calls executed with your written code.

"strace" is really effective utility for system administrators and coders to see the system calls that your program makes. It is really easy to use, just write to your terminal "strace programName" exp. "strace ./a.out" like ordinary compiled C code. It give output something like this; (I have interesting name of directory "01-um-getpid$" includes the a.out file. Do not be confused!)

erogol@ubuntu:~/Desktop/01-um-getpid$ strace ./a.out
execve("./a.out", ["./a.out"], [/* 39 vars */]) = 0
brk(0)                                  = 0x186e000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3c3d4d8000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=123841, ...}) = 0
mmap(NULL, 123841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f3c3d4b9000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240\356\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1572232, ...}) = 0
mmap(NULL, 3680296, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f3c3cf37000
mprotect(0x7f3c3d0b1000, 2093056, PROT_NONE) = 0
mmap(0x7f3c3d2b0000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x179000) = 0x7f3c3d2b0000
mmap(0x7f3c3d2b5000, 18472, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f3c3d2b5000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3c3d4b8000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3c3d4b7000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f3c3d4b6000
arch_prctl(ARCH_SET_FS, 0x7f3c3d4b7700) = 0
mprotect(0x7f3c3d2b0000, 16384, PROT_READ) = 0
mprotect(0x600000, 4096, PROT_READ)     = 0
mprotect(0x7f3c3d4da000, 4096, PROT_READ) = 0
munmap(0x7f3c3d4b9000, 123841)          = 0
getpid()                                = 9376
exit_group(0)                           = ?

The numbers that are at the end of the lines are the System Call numbers and the beginning of the lines are the sys. call names. That is all...