当我们使用golang进行文件的创建，网络的创建，我们有没有想过， 它是如果调用的，熟悉linux的朋友应该很清楚，在linux系统中，提供了C语言的一套系统调用的外壳。 而golang通过自己封装了系统调用的函数，配置系统调用表，我们可以调用系统提供了例如创建文件，创建套接字等等一系列内核操作。
下面的代码是golang封装的系统调用的函数，而Syscall和RawSyscall的区别在于，前者是被golang自己runtime管理，可以在任何的goroutine中使用， 而后者没有被runtime管理，也就是说出现阻塞的话，会阻塞掉整个程序，因此大多数情况下使用第一个，只有当我们确定，我们的系统调用不会阻塞时使用。
func Syscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
如何知道系统调用的编号以及对应编号的作用了，如果熟悉linux编程的同学，应该是非常清楚的，但是也有很多同学没有这方面的开发经验。 因此在这里，详细列出golang.org/x/unix包下面对应的系统调用，介绍每个系统调用的具体意义和用法。
所有的系统调用
// mksysnum_linux.pl /usr/include/asm/unistd_64.h
// Code generated by the command above; DO NOT EDIT.
// +build amd64,linux
package syscall
const (
SYS_READ = 0
SYS_WRITE = 1
SYS_OPEN = 2
SYS_CLOSE = 3
SYS_STAT = 4
SYS_FSTAT = 5
SYS_LSTAT = 6
SYS_POLL = 7
SYS_LSEEK = 8
SYS_MMAP = 9
SYS_MPROTECT = 10
SYS_MUNMAP = 11
SYS_BRK = 12
SYS_RT_SIGACTION = 13
SYS_RT_SIGPROCMASK = 14
SYS_RT_SIGRETURN = 15
SYS_IOCTL = 16
SYS_PREAD64 = 17
SYS_PWRITE64 = 18
SYS_READV = 19
SYS_WRITEV = 20
SYS_ACCESS = 21
SYS_PIPE = 22
SYS_SELECT = 23
SYS_SCHED_YIELD = 24
SYS_MREMAP = 25
SYS_MSYNC = 26
SYS_MINCORE = 27
SYS_MADVISE = 28
SYS_SHMGET = 29
SYS_SHMAT = 30
SYS_SHMCTL = 31
SYS_DUP = 32
SYS_DUP2 = 33
SYS_PAUSE = 34
SYS_NANOSLEEP = 35
SYS_GETITIMER = 36
SYS_ALARM = 37
SYS_SETITIMER = 38
SYS_GETPID = 39
SYS_SENDFILE = 40
SYS_SOCKET = 41
SYS_CONNECT = 42
SYS_ACCEPT = 43
SYS_SENDTO = 44
SYS_RECVFROM = 45
SYS_SENDMSG = 46
SYS_RECVMSG = 47
SYS_SHUTDOWN = 48
SYS_BIND = 49
SYS_LISTEN = 50
SYS_GETSOCKNAME = 51
SYS_GETPEERNAME = 52
SYS_SOCKETPAIR = 53
SYS_SETSOCKOPT = 54
SYS_GETSOCKOPT = 55
SYS_CLONE = 56
SYS_FORK = 57
SYS_VFORK = 58
SYS_EXECVE = 59
SYS_EXIT = 60
SYS_WAIT4 = 61
SYS_KILL = 62
SYS_UNAME = 63
SYS_SEMGET = 64
SYS_SEMOP = 65
SYS_SEMCTL = 66
SYS_SHMDT = 67
SYS_MSGGET = 68
SYS_MSGSND = 69
SYS_MSGRCV = 70
SYS_MSGCTL = 71
SYS_FCNTL = 72
SYS_FLOCK = 73
SYS_FSYNC = 74
SYS_FDATASYNC = 75
SYS_TRUNCATE = 76
SYS_FTRUNCATE = 77
SYS_GETDENTS = 78
SYS_GETCWD = 79
SYS_CHDIR = 80
SYS_FCHDIR = 81
SYS_RENAME = 82
SYS_MKDIR = 83
SYS_RMDIR = 84
SYS_CREAT = 85
SYS_LINK = 86
SYS_UNLINK = 87
SYS_SYMLINK = 88
SYS_READLINK = 89
SYS_CHMOD = 90
SYS_FCHMOD = 91
SYS_CHOWN = 92
SYS_FCHOWN = 93
SYS_LCHOWN = 94
SYS_UMASK = 95
SYS_GETTIMEOFDAY = 96
SYS_GETRLIMIT = 97
SYS_GETRUSAGE = 98
SYS_SYSINFO = 99
SYS_TIMES = 100
SYS_PTRACE = 101
SYS_GETUID = 102
SYS_SYSLOG = 103
SYS_GETGID = 104
SYS_SETUID = 105
SYS_SETGID = 106
SYS_GETEUID = 107
SYS_GETEGID = 108
SYS_SETPGID = 109
SYS_GETPPID = 110
SYS_GETPGRP = 111
SYS_SETSID = 112
SYS_SETREUID = 113
SYS_SETREGID = 114
SYS_GETGROUPS = 115
SYS_SETGROUPS = 116
SYS_SETRESUID = 117
SYS_GETRESUID = 118
SYS_SETRESGID = 119
SYS_GETRESGID = 120
SYS_GETPGID = 121
SYS_SETFSUID = 122
SYS_SETFSGID = 123
SYS_GETSID = 124
SYS_CAPGET = 125
SYS_CAPSET = 126
SYS_RT_SIGPENDING = 127
SYS_RT_SIGTIMEDWAIT = 128
SYS_RT_SIGQUEUEINFO = 129
SYS_RT_SIGSUSPEND = 130
SYS_SIGALTSTACK = 131
SYS_UTIME = 132
SYS_MKNOD = 133
SYS_USELIB = 134
SYS_PERSONALITY = 135
SYS_USTAT = 136
SYS_STATFS = 137
SYS_FSTATFS = 138
SYS_SYSFS = 139
SYS_GETPRIORITY = 140
SYS_SETPRIORITY = 141
SYS_SCHED_SETPARAM = 142
SYS_SCHED_GETPARAM = 143
SYS_SCHED_SETSCHEDULER = 144
SYS_SCHED_GETSCHEDULER = 145
SYS_SCHED_GET_PRIORITY_MAX = 146
SYS_SCHED_GET_PRIORITY_MIN = 147
SYS_SCHED_RR_GET_INTERVAL = 148
SYS_MLOCK = 149
SYS_MUNLOCK = 150
SYS_MLOCKALL = 151
SYS_MUNLOCKALL = 152
SYS_VHANGUP = 153
SYS_MODIFY_LDT = 154
SYS_PIVOT_ROOT = 155
SYS__SYSCTL = 156
SYS_PRCTL = 157
SYS_ARCH_PRCTL = 158
SYS_ADJTIMEX = 159
SYS_SETRLIMIT = 160
SYS_CHROOT = 161
SYS_SYNC = 162
SYS_ACCT = 163
SYS_SETTIMEOFDAY = 164
SYS_MOUNT = 165
SYS_UMOUNT2 = 166
SYS_SWAPON = 167
SYS_SWAPOFF = 168
SYS_REBOOT = 169
SYS_SETHOSTNAME = 170
SYS_SETDOMAINNAME = 171
SYS_IOPL = 172
SYS_IOPERM = 173
SYS_CREATE_MODULE = 174
SYS_INIT_MODULE = 175
SYS_DELETE_MODULE = 176
SYS_GET_KERNEL_SYMS = 177
SYS_QUERY_MODULE = 178
SYS_QUOTACTL = 179
SYS_NFSSERVCTL = 180
SYS_GETPMSG = 181
SYS_PUTPMSG = 182
SYS_AFS_SYSCALL = 183
SYS_TUXCALL = 184
SYS_SECURITY = 185
SYS_GETTID = 186
SYS_READAHEAD = 187
SYS_SETXATTR = 188
SYS_LSETXATTR = 189
SYS_FSETXATTR = 190
SYS_GETXATTR = 191
SYS_LGETXATTR = 192
SYS_FGETXATTR = 193
SYS_LISTXATTR = 194
SYS_LLISTXATTR = 195
SYS_FLISTXATTR = 196
SYS_REMOVEXATTR = 197
SYS_LREMOVEXATTR = 198
SYS_FREMOVEXATTR = 199
SYS_TKILL = 200
SYS_TIME = 201
SYS_FUTEX = 202
SYS_SCHED_SETAFFINITY = 203
SYS_SCHED_GETAFFINITY = 204
SYS_SET_THREAD_AREA = 205
SYS_IO_SETUP = 206
SYS_IO_DESTROY = 207
SYS_IO_GETEVENTS = 208
SYS_IO_SUBMIT = 209
SYS_IO_CANCEL = 210
SYS_GET_THREAD_AREA = 211
SYS_LOOKUP_DCOOKIE = 212
SYS_EPOLL_CREATE = 213
SYS_EPOLL_CTL_OLD = 214
SYS_EPOLL_WAIT_OLD = 215
SYS_REMAP_FILE_PAGES = 216
SYS_GETDENTS64 = 217
SYS_SET_TID_ADDRESS = 218
SYS_RESTART_SYSCALL = 219
SYS_SEMTIMEDOP = 220
SYS_FADVISE64 = 221
SYS_TIMER_CREATE = 222
SYS_TIMER_SETTIME = 223
SYS_TIMER_GETTIME = 224
SYS_TIMER_GETOVERRUN = 225
SYS_TIMER_DELETE = 226
SYS_CLOCK_SETTIME = 227
SYS_CLOCK_GETTIME = 228
SYS_CLOCK_GETRES = 229
SYS_CLOCK_NANOSLEEP = 230
SYS_EXIT_GROUP = 231
SYS_EPOLL_WAIT = 232
SYS_EPOLL_CTL = 233
SYS_TGKILL = 234
SYS_UTIMES = 235
SYS_VSERVER = 236
SYS_MBIND = 237
SYS_SET_MEMPOLICY = 238
SYS_GET_MEMPOLICY = 239
SYS_MQ_OPEN = 240
SYS_MQ_UNLINK = 241
SYS_MQ_TIMEDSEND = 242
SYS_MQ_TIMEDRECEIVE = 243
SYS_MQ_NOTIFY = 244
SYS_MQ_GETSETATTR = 245
SYS_KEXEC_LOAD = 246
SYS_WAITID = 247
SYS_ADD_KEY = 248
SYS_REQUEST_KEY = 249
SYS_KEYCTL = 250
SYS_IOPRIO_SET = 251
SYS_IOPRIO_GET = 252
SYS_INOTIFY_INIT = 253
SYS_INOTIFY_ADD_WATCH = 254
SYS_INOTIFY_RM_WATCH = 255
SYS_MIGRATE_PAGES = 256
SYS_OPENAT = 257
SYS_MKDIRAT = 258
SYS_MKNODAT = 259
SYS_FCHOWNAT = 260
SYS_FUTIMESAT = 261
SYS_NEWFSTATAT = 262
SYS_UNLINKAT = 263
SYS_RENAMEAT = 264
SYS_LINKAT = 265
SYS_SYMLINKAT = 266
SYS_READLINKAT = 267
SYS_FCHMODAT = 268
SYS_FACCESSAT = 269
SYS_PSELECT6 = 270
SYS_PPOLL = 271
SYS_UNSHARE = 272
SYS_SET_ROBUST_LIST = 273
SYS_GET_ROBUST_LIST = 274
SYS_SPLICE = 275
SYS_TEE = 276
SYS_SYNC_FILE_RANGE = 277
SYS_VMSPLICE = 278
SYS_MOVE_PAGES = 279
SYS_UTIMENSAT = 280
SYS_EPOLL_PWAIT = 281
SYS_SIGNALFD = 282
SYS_TIMERFD_CREATE = 283
SYS_EVENTFD = 284
SYS_FALLOCATE = 285
SYS_TIMERFD_SETTIME = 286
SYS_TIMERFD_GETTIME = 287
SYS_ACCEPT4 = 288
SYS_SIGNALFD4 = 289
SYS_EVENTFD2 = 290
SYS_EPOLL_CREATE1 = 291
SYS_DUP3 = 292
SYS_PIPE2 = 293
SYS_INOTIFY_INIT1 = 294
SYS_PREADV = 295
SYS_PWRITEV = 296
SYS_RT_TGSIGQUEUEINFO = 297
SYS_PERF_EVENT_OPEN = 298
SYS_RECVMMSG = 299
SYS_FANOTIFY_INIT = 300
SYS_FANOTIFY_MARK = 301
SYS_PRLIMIT64 = 302
)
接下来，分为几个场景来讲解。
远程控制
// Linux上创建线程一般使用的是pthread库 实际上linux也给我们提供了创建线程的系统调用，就是clone
SYS_CLONE =
// fork 创建一个子进程，但是不共享父进程的数据空间、堆、栈等资源的副本，只是获取它的备份
SYS_FORK = 57
// vfork 创建一个子进程，区别在于共享父进程的数据空间、堆、栈等资源的副本
// 数据空间、堆、栈等资源的副本
SYS_VFORK = 58
// execve函数作用是执行一个新的程序，程序可以是二进制的可执行程序，也可以是shell、pathon脚本
SYS_EXECVE = 59
// 中止进程
SYS_EXIT = 60
//