1: Frequently used shortcut commands
- Ctrl + A: Move to the beginning of the command line
- Ctrl + E: Move to the end of the command line
- Ctrl + U: Delete from the cursor to the beginning of the command line
2: Special variables
$? -The exit status or function return value of a command on >
[vagrant@localhost bin]$ echo $?
0The exit status is an integer value prior to 0 to 255 that is passed back to the shell by the command at the end of the command
| Common status code | instructions |
|---|---|
| 0 | Command runs successfully |
| 1 | Generic unknown error |
| 2 | Misuse of shell commands |
| 126 | Command unexecutable |
| 127 | No command found |
| 128 | Invalid exit parameter |
| 128+x | A serious error with Linux signal X |
| 130 | The command terminates with SIGINT (Ctrl+C) |
| 255 | Exit status code out of bounds |