Linux操作系统之Linux命令的返回值

前言

①Linux操作系统中，无论是启动桌面程序还是在控制台终端执行命令，所有的程序在结束时，都会返回一个数字值，这个值叫做返回值，或者称为错误号（ Error Number ）

②在控制台终端中，存在一个特殊的环境变量  $? ，保存着前一个程序的返回值。

实例

1、命令执行成功

2、命令执行失败

Linux命令返回值的含义

Linux命令执行后无论成功与否都有一个返回值，如果为 0，则表示命令执行成功，其它值则表示执行错误。

具体的错误码含义如下：

 "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"
 "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"
 "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"
 "OS error code 121: Remote I/O error"
 "OS error code 122: Disk quota exceeded"
 "OS error code 123: No medium found"
 "OS error code 124: Wrong medium type"
 "OS error code 125: Operation canceled"
 "OS error code 126: Required key not available"
 "OS error code 127: Key has expired"
 "OS error code 128: Key has been revoked"
 "OS error code 129: Key was rejected by service"
 "OS error code 130: Owner died"
 "OS error code 131: State not recoverable"