在linux中进程退出之后会有一个退出状态，可以通过echo ?进行查看。
如果说把进程比作一个人（病人和正常人）的话那么进程退出码就可以看做是病人的症状！
挺好用的如果你发现执行某个命令或自己编写的代码生成的ELF文件发现毛都没发生过就可以通过该指令进行查看。
那么不同的退查状态又说明进程发生了什么了呢？可以通过perror进行查看！下面是通过通过perror指令查看得到的所有的退出码的解析(en)。
OS error code 0: Success
OS error code 1: Operation not permitted
OS error code 2: No such file or directory
OS error code 3: No such process
OS error code 4: Interrupted system call
OS error code 5: Input/output error
OS error code 6: No such device or address
OS error code 7: Argument list too long
OS error code 8: Exec format error
OS error code 9: Bad file descriptor
OS error code 10: No child processes
OS error code 11: Resource temporarily unavailable
OS error code 12: Cannot allocate memory
OS error code 13: Permission denied
OS error code 14: Bad address
OS error code 15: Block device required
OS error code 16: Device or resource busy
OS error code 17: File exists
OS error code 18: Invalid cross-device link
OS error code 19: No such device
OS error code 20: Not a directory
OS error code 21: Is a directory
OS error code 22: Invalid argument
OS error code 23: Too many open files in system
OS error code 24: Too many open files
OS error code 25: Inappropriate ioctl for device
OS error code 26: Text file busy
OS error code 27: File too large
OS error code 28: No space left on device
OS error code 29: Illegal seek
OS error code 30: Read-only file system
OS error code 31: Too many links
OS error code 32: Broken pipe
OS error code 33: Numerical argument out of domain
OS error code 34: Numerical result out of range
OS error code 35: Resource deadlock avoided
OS error code 36: File name too long
OS error code 37: No locks available
OS error code 38: Function not implemented
OS error code 39: Directory not empty
OS error code 40: Too many levels of symbolic links
Illegal error code: 41
OS error code 42: No message of desired type
OS error code 43: Identifier removed
OS error code 44: Channel number out of range
OS error code 45: Level 2 not synchronized
OS error code 46: Level 3 halted
OS error code 47: Level 3 reset
OS error code 48: Link number out of range
OS error code 49: Protocol driver not attached
OS error code 50: No CSI structure available
OS error code 51: Level 2 halted
OS error code 52: Invalid exchange
OS error code 53: Invalid request descriptor
OS error code 54: Exchange full
OS error code 55: No anode
OS error code 56: Invalid request code
OS error code 57: Invalid slot
Illegal error code: 58
OS error code 59: Bad font file format
OS error code 60: Device not a stream
OS error code 61: No data available
OS error code 62: Timer expired
OS error code 63: Out of streams resources
OS error code 64: Machine is not on the network
OS error code 65: Package not installed
OS error code 66: Object is remote
OS error code 67: Link has been severed
OS error code 68: Advertise error
OS error code 69: Srmount error
OS error code 70: Communication error on send
OS error code 71: Protocol error
OS error code 72: Multihop attempted
OS error code 73: RFS specific error
OS error code 74: Bad message
OS error code 75: Value too large for defined data type
OS error code 76: Name not unique on network
OS error code 77: File descriptor in bad state
OS error code 78: Remote address changed
OS error code 79: Can not access a needed shared library
OS error code 80: Accessing a corrupted shared library
OS error code 81: .lib section in a.out corrupted
OS error code 82: Attempting to link in too many shared libraries
OS error code 83: Cannot exec a shared library directly
OS error code 84: Invalid or incomplete multibyte or wide character
OS error code 85: Interrupted system call should be restarted
OS error code 86: Streams pipe error
OS error code 87: Too many users
OS error code 88: Socket operation on non-socket
OS error code 89: Destination address required
OS error code 90: Message too long
OS error code 91: Protocol wrong type for socket
OS error code 92: Protocol not available
OS error code 93: Protocol not supported
OS error code 94: Socket type not supported
OS error code 95: Operation not supported
OS error code 96: Protocol family not supported
OS error code 97: Address family not supported by protocol
OS error code 98: Address already in use
OS error code 99: Cannot assign requested address
OS error code 100: Network is down
OS error code 101: Network is unreachable
OS error code 102: Network dropped connection on reset
OS error code 103: Software caused connection abort
OS error code 104: Connection reset by peer
OS error code 105: No buffer space available
OS error code 106: Transport endpoint is already connected
OS error code 107: Transport endpoint is not connected
OS error code 108: Cannot send after transport endpoint shutdown
OS error code 109: Too many references: cannot splice
OS error code 110: Connection timed out
OS error code 111: Connection refused
OS error code 112: Host is down
OS error code 113: No route to host
OS error code 114: Operation already in progress
OS error code 115: Operation now in progress
OS error code 116: Stale NFS file handle
OS error code 117: Structure needs cleaning
OS error code 118: Not a XENIX named type file
OS error code 119: No XENIX semaphores available
OS error code 120: Is a named type file
MySQL error code 120: Didn't find key on read or update
OS error code 121: Remote I/O error
MySQL error code 121: Duplicate key on write or update
OS error code 122: Disk quota exceeded
MySQL error code 122: Internal (unspecified) error in handler
OS error code 123: No medium found
MySQL error code 123: Someone has changed the row since it was read (while the table was locked to prevent it)
OS error code 124: Wrong medium type
MySQL error code 124: Wrong index given to function
OS error code 125: Operation canceled
MySQL error code 125: Undefined handler error 125
OS error code 126: Required key not available
MySQL error code 126: Index file is crashed
OS error code 127: Key has expired
MySQL error code 127: Record file is crashed
OS error code 128: Key has been revoked
MySQL error code 128: Out of memory in engine
OS error code 129: Key was rejected by service
MySQL error code 129: Undefined handler error 129
OS error code 130: Owner died
MySQL error code 130: Incorrect file format
OS error code 131: State not recoverable
MySQL error code 131: Command not supported by database
OS error code 132: Operation not possible due to RF-kill
MySQL error code 132: Old database file
MySQL error code 133: No record read before update
MySQL error code 134: Record was already deleted (or record file crashed)
MySQL error code 135: No more room in record file
MySQL error code 136: No more room in index file
MySQL error code 137: No more records (read after end of file)
MySQL error code 138: Unsupported extension used for table
MySQL error code 139: Too big row
MySQL error code 140: Wrong create options
MySQL error code 141: Duplicate unique key or constraint on write or update
MySQL error code 142: Unknown character set used in table
MySQL error code 143: Conflicting table definitions in sub-tables of MERGE table
MySQL error code 144: Table is crashed and last repair failed
MySQL error code 145: Table was marked as crashed and should be repaired
MySQL error code 146: Lock timed out; Retry transaction
MySQL error code 147: Lock table is full; Restart program with a larger locktable
MySQL error code 148: Updates are not allowed under a read only transactions
MySQL error code 149: Lock deadlock; Retry transaction
MySQL error code 150: Foreign key constraint is incorrectly formed
MySQL error code 151: Cannot add a child row
MySQL error code 152: Cannot delete a parent row
MySQL error code 153: No savepoint with that name
MySQL error code 154: Non unique key block size
MySQL error code 155: The table does not exist in engine
MySQL error code 156: The table already existed in storage engine
MySQL error code 157: Could not connect to storage engine
MySQL error code 158: Unexpected null pointer found when using spatial index
MySQL error code 159: The table changed in storage engine
MySQL error code 160: There's no partition in table for the given value
MySQL error code 161: Row-based binlogging of row failed
MySQL error code 162: Index needed in foreign key constraint
MySQL error code 163: Upholding foreign key constraints would lead to a duplicate key error in some other table
MySQL error code 164: Table needs to be upgraded before it can be used
MySQL error code 165: Table is read only
MySQL error code 166: Failed to get next auto increment value
MySQL error code 167: Failed to set row auto increment value
MySQL error code 168: Unknown (generic) error from engine
MySQL error code 169: Record is the same
MySQL error code 170: It is not possible to log this statement
MySQL error code 171: The event was corrupt, leading to illegal data being read
MySQL error code 172: The table is of a new format not supported by this version
MySQL error code 173: The event could not be processed no other hanlder error happened
MySQL error code 174: Got a fatal error during initialzaction of handler
MySQL error code 175: File to short; Expected more data in file
MySQL error code 176: Read page with wrong checksum
MySQL error code 177: Too many active concurrent transactions
Illegal error code: 178
Illegal error code: 179
Illegal error code: 180
Illegal error code: 181
Illegal error code: 182
Illegal error code: 183
Illegal error code: 184
Illegal error code: 185
Illegal error code: 186
Illegal error code: 187
Illegal error code: 188
Illegal error code: 189
Illegal error code: 190
Illegal error code: 191
Illegal error code: 192
Illegal error code: 193
Illegal error code: 194
Illegal error code: 195
Illegal error code: 196
Illegal error code: 197
Illegal error code: 198
Illegal error code: 199
Illegal error code: 200
Illegal error code: 201
Illegal error code: 202
Illegal error code: 203
Illegal error code: 204
Illegal error code: 205
Illegal error code: 206
Illegal error code: 207
Illegal error code: 208
Illegal error code: 209
Illegal error code: 210
Illegal error code: 211
Illegal error code: 212
Illegal error code: 213
Illegal error code: 214
Illegal error code: 215
Illegal error code: 216
Illegal error code: 217
Illegal error code: 218
Illegal error code: 219
Illegal error code: 220
Illegal error code: 221
Illegal error code: 222
Illegal error code: 223
Illegal error code: 224
Illegal error code: 225
Illegal error code: 226
Illegal error code: 227
Illegal error code: 228
Illegal error code: 229
Illegal error code: 230
Illegal error code: 231
Illegal error code: 232
Illegal error code: 233
Illegal error code: 234
Illegal error code: 235
Illegal error code: 236
Illegal error code: 237
Illegal error code: 238
Illegal error code: 239
Illegal error code: 240
Illegal error code: 241
Illegal error code: 242
Illegal error code: 243
Illegal error code: 244
Illegal error code: 245
Illegal error code: 246
Illegal error code: 247
Illegal error code: 248
Illegal error code: 249
Illegal error code: 250
Illegal error code: 251
Illegal error code: 252
Illegal error code: 253
Illegal error code: 254
Illegal error code: 255
知道了这些退出码之后自己写shell程序的时候就可以选择适当的退出码了！
内核资料直通车：Linux内核源码技术学习路线+视频教程代码资料
学习直通车：Linux内核源码/内存调优/文件系统/进程管理/设备驱动/网络协议栈
原文作者：精通Linux内核
原文地址：Linux内核：进程管理——进程退出状态码 - 知乎（版权归原文作者所有，侵权留言联系删除）