Process Console
process_console is a capsule that implements a small shell over the UART that
allows a terminal to inspect the kernel and control userspace processes.
Setup
Here is how to add process_console to a board's main.rs (the example is
taken from the microbit's implementation of the Process console):
#![allow(unused)] fn main() { let process_printer = components::process_printer::ProcessPrinterTextComponent::new() .finalize(components::process_printer_text_component_static!()); let _process_console = components::process_console::ProcessConsoleComponent::new( board_kernel, uart_mux, mux_alarm, process_printer, Some(reset_function), ) .finalize(components::process_console_component_static!( nrf52833::rtc::Rtc )); let _ = _process_console.start(); }
Using Process Console
With this capsule properly added to a board's main.rs and the Tock kernel
loaded to the board, make sure there is a serial connection to the board.
Likely, this just means connecting a USB cable from a computer to the board.
Next, establish a serial console connection to the board. An easy way to do this
is to run:
$ tockloader listen
[INFO ] No device name specified. Using default name "tock".
[INFO ] No serial port with device name "tock" found.
[INFO ] Found 2 serial ports.
Multiple serial port options found. Which would you like to use?
[0] /dev/ttyS4 - n/a
[1] /dev/ttyACM0 - "BBC micro:bit CMSIS-DAP" - mbed Serial Port
Which option? [0] 1
[INFO ] Using "/dev/ttyACM0 - "BBC micro:bit CMSIS-DAP" - mbed Serial Port".
[INFO ] Listening for serial output.
tock$
Commands
This module provides a simple text-based console to inspect and control which processes are running. The console has several commands:
help- prints the available commands and argumentslist- lists the current processes with their IDs and running statestatus- prints the current system statusstart n- starts the stopped process with name nstop n- stops the process with name nterminate n- terminates the running process with name n, moving it to the Terminated stateboot n- tries to restart a Terminated process with name nfault n- forces the process with name n into a fault statepanic- causes the kernel to run the panic handlerreset- causes the board to resetkernel- prints the kernel memory mapprocess n- prints the memory map of process with name nconsole-start- activate the process consoleconsole-stop- deactivate the process console
For the examples below we will have 2 processes on the board: blink (which
will blink all the LEDs that are connected to the kernel), and c_hello (which
prints 'Hello World' when the console is started). Also, a micro:bit v2 board
was used as support for the commands, so the results may vary on other devices.
We will assume that the user has a serial connection to the board, either by
using tockloader or another serial port software. With that console open, you
can issue commands.
help
To get a list of the available commands, use the help command:
tock$ help
Welcome to the process console.
Valid commands are: help status list stop start fault boot terminate process kernel panic
list
To see all of the processes on the board, use list:
tock$ list
PID Name Quanta Syscalls Restarts Grants State
0 blink 0 26818 0 1/14 Yielded
1 c_hello 0 8 0 1/14 Yielded
list Command Fields
PID: The identifier for the process. This can change if the process restarts.Name: The process name.Quanta: How many times this process has exceeded its allotted time quanta.Syscalls: The number of system calls the process has made to the kernel.Restarts: How many times this process has crashed and been restarted by the kernel.Grants: The number of grants that have been initialized for the process out of the total number of grants defined by the kernel.State: The state the process is in.
status
To get a general view of the system, use the status command:
tock$ status
Total processes: 2
Active processes: 2
Timeslice expirations: 0
start and stop
You can control processes with the start and stop commands:
tock$ stop blink
Process blink stopped
tock$ list
PID Name Quanta Syscalls Restarts Grants State
2 blink 0 22881 1 1/14 StoppedYielded
1 c_hello 0 8 0 1/14 Yielded
tock$ start blink
Process blink resumed.
tock$ list
PID Name Quanta Syscalls Restarts Grants State
2 blink 0 23284 1 1/14 Yielded
1 c_hello 0 8 0 1/14 Yielded
terminate and boot
You can kill a process with terminate and then restart it with boot:
tock$ terminate blink
Process blink terminated
tock$ list
PID Name Quanta Syscalls Restarts Grants State
2 blink 0 25640 1 0/14 Terminated
1 c_hello 0 8 0 1/14 Yielded
tock$ boot blink
tock$ list
PID Name Quanta Syscalls Restarts Grants State
3 blink 0 251 2 1/14 Yielded
1 c_hello 0 8 0 1/14 Yielded
fault
To force a process into a fault state, you should use the fault command:
tock$ fault blink
panicked at 'Process blink had a fault', kernel/src/process_standard.rs:412:17
Kernel version 899d73cdd
---| No debug queue found. You can set it with the DebugQueue component.
---| Cortex-M Fault Status |---
No Cortex-M faults detected.
---| App Status |---
𝐀𝐩𝐩: blink - [Faulted]
Events Queued: 0 Syscall Count: 2359 Dropped Upcall Count: 0
Restart Count: 0
Last Syscall: Yield { which: 1, address: 0x0 }
Completion Code: None
╔═══════════╤══════════════════════════════════════════╗
║ Address │ Region Name Used | Allocated (bytes) ║
╚0x20006000═╪══════════════════════════════════════════╝
│ Grant Ptrs 112
│ Upcalls 320
│ Process 920
0x20005AB8 ┼───────────────────────────────────────────
│ ▼ Grant 24
0x20005AA0 ┼───────────────────────────────────────────
│ Unused
0x200049FC ┼───────────────────────────────────────────
│ ▲ Heap 0 | 4260 S
0x200049FC ┼─────────────────────────────────────────── R
│ Data 508 | 508 A
0x20004800 ┼─────────────────────────────────────────── M
│ ▼ Stack 232 | 2048
0x20004718 ┼───────────────────────────────────────────
│ Unused
0x20004000 ┴───────────────────────────────────────────
.....
0x00040800 ┬─────────────────────────────────────────── F
│ App Flash 1996 L
0x00040034 ┼─────────────────────────────────────────── A
│ Protected 52 S
0x00040000 ┴─────────────────────────────────────────── H
R0 : 0x00000001 R6 : 0x000406B0
R1 : 0x00000000 R7 : 0x20004000
R2 : 0x0000000B R8 : 0x00000000
R3 : 0x0000000B R10: 0x00000000
R4 : 0x200047AB R11: 0x00000000
R5 : 0x200047AB R12: 0x20004750
R9 : 0x20004800 (Static Base Register)
SP : 0x20004778 (Process Stack Pointer)
LR : 0x00040457
PC : 0x0004045E
YPC : 0x0004045E
APSR: N 0 Z 0 C 1 V 0 Q 0
GE 0 0 0 0
EPSR: ICI.IT 0x00
ThumbBit true
Total number of grant regions defined: 14
Grant 0 : -- Grant 5 : -- Grant 10 : --
Grant 1 : -- Grant 6 : -- Grant 11 : --
Grant 2 0x0: 0x20005aa0 Grant 7 : -- Grant 12 : --
Grant 3 : -- Grant 8 : -- Grant 13 : --
Grant 4 : -- Grant 9 : --
Cortex-M MPU
Region 0: [0x20004000:0x20005000], length: 4096 bytes; ReadWrite (0x3)
Sub-region 0: [0x20004000:0x20004200], Enabled
Sub-region 1: [0x20004200:0x20004400], Enabled
Sub-region 2: [0x20004400:0x20004600], Enabled
Sub-region 3: [0x20004600:0x20004800], Enabled
Sub-region 4: [0x20004800:0x20004A00], Enabled
Sub-region 5: [0x20004A00:0x20004C00], Disabled
Sub-region 6: [0x20004C00:0x20004E00], Disabled
Sub-region 7: [0x20004E00:0x20005000], Disabled
Region 1: Unused
Region 2: [0x00040000:0x00040800], length: 2048 bytes; UnprivilegedReadOnly (0x2)
Sub-region 0: [0x00040000:0x00040100], Enabled
Sub-region 1: [0x00040100:0x00040200], Enabled
Sub-region 2: [0x00040200:0x00040300], Enabled
Sub-region 3: [0x00040300:0x00040400], Enabled
Sub-region 4: [0x00040400:0x00040500], Enabled
Sub-region 5: [0x00040500:0x00040600], Enabled
Sub-region 6: [0x00040600:0x00040700], Enabled
Sub-region 7: [0x00040700:0x00040800], Enabled
Region 3: Unused
Region 4: Unused
Region 5: Unused
Region 6: Unused
Region 7: Unused
To debug, run `make debug RAM_START=0x20004000 FLASH_INIT=0x4005d`
in the app's folder and open the .lst file.
𝐀𝐩𝐩: c_hello - [Yielded]
Events Queued: 0 Syscall Count: 8 Dropped Upcall Count: 0
Restart Count: 0
Last Syscall: Yield { which: 1, address: 0x0 }
Completion Code: None
╔═══════════╤══════════════════════════════════════════╗
║ Address │ Region Name Used | Allocated (bytes) ║
╚0x20008000═╪══════════════════════════════════════════╝
│ Grant Ptrs 112
│ Upcalls 320
│ Process 920
0x20007AB8 ┼───────────────────────────────────────────
│ ▼ Grant 76
0x20007A6C ┼───────────────────────────────────────────
│ Unused
0x20006A04 ┼───────────────────────────────────────────
│ ▲ Heap 0 | 4200 S
0x20006A04 ┼─────────────────────────────────────────── R
│ Data 516 | 516 A
0x20006800 ┼─────────────────────────────────────────── M
│ ▼ Stack 128 | 2048
0x20006780 ┼───────────────────────────────────────────
│ Unused
0x20006000 ┴───────────────────────────────────────────
.....
0x00041000 ┬─────────────────────────────────────────── F
│ App Flash 1996 L
0x00040834 ┼─────────────────────────────────────────── A
│ Protected 52 S
0x00040800 ┴─────────────────────────────────────────── H
R0 : 0x00000001 R6 : 0x00040C50
R1 : 0x00000000 R7 : 0x20006000
R2 : 0x00000000 R8 : 0x00000000
R3 : 0x00000000 R10: 0x00000000
R4 : 0x00040834 R11: 0x00000000
R5 : 0x20006000 R12: 0x200067F0
R9 : 0x20006800 (Static Base Register)
SP : 0x200067D0 (Process Stack Pointer)
LR : 0x00040A3F
PC : 0x00040A46
YPC : 0x00040A46
APSR: N 0 Z 0 C 1 V 0 Q 0
GE 0 0 0 0
EPSR: ICI.IT 0x00
ThumbBit true
Total number of grant regions defined: 14
Grant 0 : -- Grant 5 : -- Grant 10 : --
Grant 1 : -- Grant 6 : -- Grant 11 : --
Grant 2 : -- Grant 7 : -- Grant 12 : --
Grant 3 : -- Grant 8 : -- Grant 13 : --
Grant 4 0x1: 0x20007a6c Grant 9 : --
Cortex-M MPU
Region 0: [0x20006000:0x20007000], length: 4096 bytes; ReadWrite (0x3)
Sub-region 0: [0x20006000:0x20006200], Enabled
Sub-region 1: [0x20006200:0x20006400], Enabled
Sub-region 2: [0x20006400:0x20006600], Enabled
Sub-region 3: [0x20006600:0x20006800], Enabled
Sub-region 4: [0x20006800:0x20006A00], Enabled
Sub-region 5: [0x20006A00:0x20006C00], Enabled
Sub-region 6: [0x20006C00:0x20006E00], Disabled
Sub-region 7: [0x20006E00:0x20007000], Disabled
Region 1: Unused
Region 2: [0x00040800:0x00041000], length: 2048 bytes; UnprivilegedReadOnly (0x2)
Sub-region 0: [0x00040800:0x00040900], Enabled
Sub-region 1: [0x00040900:0x00040A00], Enabled
Sub-region 2: [0x00040A00:0x00040B00], Enabled
Sub-region 3: [0x00040B00:0x00040C00], Enabled
Sub-region 4: [0x00040C00:0x00040D00], Enabled
Sub-region 5: [0x00040D00:0x00040E00], Enabled
Sub-region 6: [0x00040E00:0x00040F00], Enabled
Sub-region 7: [0x00040F00:0x00041000], Enabled
Region 3: Unused
Region 4: Unused
Region 5: Unused
Region 6: Unused
Region 7: Unused
To debug, run `make debug RAM_START=0x20006000 FLASH_INIT=0x4085d`
in the app's folder and open the .lst file.
panic
You can also force a kernel panic with the panic command:
tock$ panic
panicked at 'Process Console forced a kernel panic.', capsules/src/process_console.rs:959:29
Kernel version 899d73cdd
---| No debug queue found. You can set it with the DebugQueue component.
---| Cortex-M Fault Status |---
No Cortex-M faults detected.
---| App Status |---
𝐀𝐩𝐩: blink - [Yielded]
Events Queued: 0 Syscall Count: 1150 Dropped Upcall Count: 0
Restart Count: 0
Last Syscall: Yield { which: 1, address: 0x0 }
Completion Code: None
╔═══════════╤══════════════════════════════════════════╗
║ Address │ Region Name Used | Allocated (bytes) ║
╚0x20006000═╪══════════════════════════════════════════╝
│ Grant Ptrs 112
│ Upcalls 320
│ Process 920
0x20005AB8 ┼───────────────────────────────────────────
│ ▼ Grant 24
0x20005AA0 ┼───────────────────────────────────────────
│ Unused
0x200049FC ┼───────────────────────────────────────────
│ ▲ Heap 0 | 4260 S
0x200049FC ┼─────────────────────────────────────────── R
│ Data 508 | 508 A
0x20004800 ┼─────────────────────────────────────────── M
│ ▼ Stack 232 | 2048
0x20004718 ┼───────────────────────────────────────────
│ Unused
0x20004000 ┴───────────────────────────────────────────
.....
0x00040800 ┬─────────────────────────────────────────── F
│ App Flash 1996 L
0x00040034 ┼─────────────────────────────────────────── A
│ Protected 52 S
0x00040000 ┴─────────────────────────────────────────── H
R0 : 0x00000001 R6 : 0x000406B0
R1 : 0x00000000 R7 : 0x20004000
R2 : 0x00000004 R8 : 0x00000000
R3 : 0x00000004 R10: 0x00000000
R4 : 0x200047AB R11: 0x00000000
R5 : 0x200047AB R12: 0x20004750
R9 : 0x20004800 (Static Base Register)
SP : 0x20004778 (Process Stack Pointer)
LR : 0x00040457
PC : 0x0004045E
YPC : 0x0004045E
APSR: N 0 Z 0 C 1 V 0 Q 0
GE 0 0 0 0
EPSR: ICI.IT 0x00
ThumbBit true
Total number of grant regions defined: 14
Grant 0 : -- Grant 5 : -- Grant 10 : --
Grant 1 : -- Grant 6 : -- Grant 11 : --
Grant 2 0x0: 0x20005aa0 Grant 7 : -- Grant 12 : --
Grant 3 : -- Grant 8 : -- Grant 13 : --
Grant 4 : -- Grant 9 : --
Cortex-M MPU
Region 0: [0x20004000:0x20005000], length: 4096 bytes; ReadWrite (0x3)
Sub-region 0: [0x20004000:0x20004200], Enabled
Sub-region 1: [0x20004200:0x20004400], Enabled
Sub-region 2: [0x20004400:0x20004600], Enabled
Sub-region 3: [0x20004600:0x20004800], Enabled
Sub-region 4: [0x20004800:0x20004A00], Enabled
Sub-region 5: [0x20004A00:0x20004C00], Disabled
Sub-region 6: [0x20004C00:0x20004E00], Disabled
Sub-region 7: [0x20004E00:0x20005000], Disabled
Region 1: Unused
Region 2: [0x00040000:0x00040800], length: 2048 bytes; UnprivilegedReadOnly (0x2)
Sub-region 0: [0x00040000:0x00040100], Enabled
Sub-region 1: [0x00040100:0x00040200], Enabled
Sub-region 2: [0x00040200:0x00040300], Enabled
Sub-region 3: [0x00040300:0x00040400], Enabled
Sub-region 4: [0x00040400:0x00040500], Enabled
Sub-region 5: [0x00040500:0x00040600], Enabled
Sub-region 6: [0x00040600:0x00040700], Enabled
Sub-region 7: [0x00040700:0x00040800], Enabled
Region 3: Unused
Region 4: Unused
Region 5: Unused
Region 6: Unused
Region 7: Unused
To debug, run `make debug RAM_START=0x20004000 FLASH_INIT=0x4005d`
in the app's folder and open the .lst file.
𝐀𝐩𝐩: c_hello - [Yielded]
Events Queued: 0 Syscall Count: 8 Dropped Upcall Count: 0
Restart Count: 0
Last Syscall: Yield { which: 1, address: 0x0 }
Completion Code: None
╔═══════════╤══════════════════════════════════════════╗
║ Address │ Region Name Used | Allocated (bytes) ║
╚0x20008000═╪══════════════════════════════════════════╝
│ Grant Ptrs 112
│ Upcalls 320
│ Process 920
0x20007AB8 ┼───────────────────────────────────────────
│ ▼ Grant 76
0x20007A6C ┼───────────────────────────────────────────
│ Unused
0x20006A04 ┼───────────────────────────────────────────
│ ▲ Heap 0 | 4200 S
0x20006A04 ┼─────────────────────────────────────────── R
│ Data 516 | 516 A
0x20006800 ┼─────────────────────────────────────────── M
│ ▼ Stack 128 | 2048
0x20006780 ┼───────────────────────────────────────────
│ Unused
0x20006000 ┴───────────────────────────────────────────
.....
0x00041000 ┬─────────────────────────────────────────── F
│ App Flash 1996 L
0x00040834 ┼─────────────────────────────────────────── A
│ Protected 52 S
0x00040800 ┴─────────────────────────────────────────── H
R0 : 0x00000001 R6 : 0x00040C50
R1 : 0x00000000 R7 : 0x20006000
R2 : 0x00000000 R8 : 0x00000000
R3 : 0x00000000 R10: 0x00000000
R4 : 0x00040834 R11: 0x00000000
R5 : 0x20006000 R12: 0x200067F0
R9 : 0x20006800 (Static Base Register)
SP : 0x200067D0 (Process Stack Pointer)
LR : 0x00040A3F
PC : 0x00040A46
YPC : 0x00040A46
APSR: N 0 Z 0 C 1 V 0 Q 0
GE 0 0 0 0
EPSR: ICI.IT 0x00
ThumbBit true
Total number of grant regions defined: 14
Grant 0 : -- Grant 5 : -- Grant 10 : --
Grant 1 : -- Grant 6 : -- Grant 11 : --
Grant 2 : -- Grant 7 : -- Grant 12 : --
Grant 3 : -- Grant 8 : -- Grant 13 : --
Grant 4 0x1: 0x20007a6c Grant 9 : --
Cortex-M MPU
Region 0: [0x20006000:0x20007000], length: 4096 bytes; ReadWrite (0x3)
Sub-region 0: [0x20006000:0x20006200], Enabled
Sub-region 1: [0x20006200:0x20006400], Enabled
Sub-region 2: [0x20006400:0x20006600], Enabled
Sub-region 3: [0x20006600:0x20006800], Enabled
Sub-region 4: [0x20006800:0x20006A00], Enabled
Sub-region 5: [0x20006A00:0x20006C00], Enabled
Sub-region 6: [0x20006C00:0x20006E00], Disabled
Sub-region 7: [0x20006E00:0x20007000], Disabled
Region 1: Unused
Region 2: [0x00040800:0x00041000], length: 2048 bytes; UnprivilegedReadOnly (0x2)
Sub-region 0: [0x00040800:0x00040900], Enabled
Sub-region 1: [0x00040900:0x00040A00], Enabled
Sub-region 2: [0x00040A00:0x00040B00], Enabled
Sub-region 3: [0x00040B00:0x00040C00], Enabled
Sub-region 4: [0x00040C00:0x00040D00], Enabled
Sub-region 5: [0x00040D00:0x00040E00], Enabled
Sub-region 6: [0x00040E00:0x00040F00], Enabled
Sub-region 7: [0x00040F00:0x00041000], Enabled
Region 3: Unused
Region 4: Unused
Region 5: Unused
Region 6: Unused
Region 7: Unused
To debug, run `make debug RAM_START=0x20006000 FLASH_INIT=0x4085d`
in the app's folder and open the .lst file.
reset
You can also reset the board with the reset command:
tock$ reset
kernel
You can view the kernel memory map with the kernel command:
tock$ kernel
Kernel version: 2.1 (build 899d73cdd)
╔═══════════╤══════════════════════════════╗
║ Address │ Region Name Used (bytes) ║
╚0x20003DAC═╪══════════════════════════════╝
│ BSS 11692
0x20001000 ┼─────────────────────────────── S
│ Relocate 0 R
0x20001000 ┼─────────────────────────────── A
│ ▼ Stack 4096 M
0x20000000 ┼───────────────────────────────
.....
0x0001A000 ┼─────────────────────────────── F
│ RoData 27652 L
0x000133FC ┼─────────────────────────────── A
│ Code 78844 S
0x00000000 ┼─────────────────────────────── H
process
You can also view the memory map for a process with the process command:
tock$ process c_hello
𝐀𝐩𝐩: c_hello - [Yielded]
Events Queued: 0 Syscall Count: 8 Dropped Upcall Count: 0
Restart Count: 0
Last Syscall: Yield { which: 1, address: 0x0 }
Completion Code: None
╔═══════════╤══════════════════════════════════════════╗
║ Address │ Region Name Used | Allocated (bytes) ║
╚0x20008000═╪══════════════════════════════════════════╝
│ Grant Ptrs 112
│ Upcalls 320
│ Process 920
0x20007AB8 ┼───────────────────────────────────────────
│ ▼ Grant 76
0x20007A6C ┼───────────────────────────────────────────
│ Unused
0x20006A04 ┼───────────────────────────────────────────
│ ▲ Heap 0 | 4200 S
0x20006A04 ┼─────────────────────────────────────────── R
│ Data 516 | 516 A
0x20006800 ┼─────────────────────────────────────────── M
│ ▼ Stack 128 | 2048
0x20006780 ┼───────────────────────────────────────────
│ Unused
0x20006000 ┴───────────────────────────────────────────
.....
0x00041000 ┬─────────────────────────────────────────── F
│ App Flash 1996 L
0x00040834 ┼─────────────────────────────────────────── A
│ Protected 52 S
0x00040800 ┴─────────────────────────────────────────── H
console-start
This command activates the process console so that it responds to commands and
shows the prompt. This reverses console-stop.
console-stop
This command puts the process console in a hibernation state. The console is
still running in the sense that it is receiving UART data, but it will not
respond to any commands other than console-start. It will also not show the
prompt.
The purpose of this mode is to "free up" the general UART console for apps that use the console extensively or interactively.
The console can be re-activated with console-start.
Features
Command History
You can use the up and down arrows to scroll through the command history and to
view the previous commands you have run. If you inserted more commands than the
command history can hold, oldest commands will be overwritten. You can view the
commands in bidirectional order, up arrow for oldest commands and down arrow
for newest.
If the user custom size for the history is set to 0, the history will be
disabled and the rust compiler will be able to optimize the binary file by
removing dead code. If you are typing a command and accidentally press the
up arrow key, you can press down arrow in order to retrieve the command you
were typing. If you scroll through the history and you want to edit a command
and accidentally press the up or down arrow key, scroll to the bottom of the
history and you will get back to the command you were typing.
Here is how to add a custom size for the command history used by the
ProcessConsole structure to keep track of the typed commands, in the main.rs
of boards:
#![allow(unused)] fn main() { const COMMAND_HISTORY_LEN : usize = 30; pub struct Platform { ... pconsole: &'static capsules::process_console::ProcessConsole< 'static, COMMAND_HISTORY_LEN, // or { capsules::process_console::DEFAULT_COMMAND_HISTORY_LEN } // for the default behaviour VirtualMuxAlarm<'static, nrf52840::rtc::Rtc<'static>>, components::process_console::Capability, >, ... } let _process_console = components::process_console::ProcessConsoleComponent::new( board_kernel, uart_mux, mux_alarm, process_printer, Some(reset_function), ) .finalize(components::process_console_component_static!( nrf52833::rtc::Rtc, COMMAND_HISTORY_LEN // or nothing for the default behaviour )); }
Note: In order to disable any functionality for the command history set the
COMMAND_HISTORY_LENto0or1(the history will be disabled for a size of1, because the first position from the command history is reserved for accidents by pressingupordownarrow key).
Command Navigation
Using Left and Right arrow keys you can navigate in a command, in order to
move the cursor to your desired position in a command. By pressing Home key
the cursor will be moved to the beginning of the command and by pressing End
key the cursor will be moved to the end of the command that is currently
displayed. When typing a character, it will be displayed under the cursor
(basically it will be inserted in the command at the cursor position). After
that the cursor will advance to next position (to the right). If you press
backspace the character before the cursor will be removed (the opposite action
of inserting a character) and the cursor will advance to left by one position.
Using Delete key, you can remove the cursor under the cursor. In this case the
cursor will not advance to any new position.
Pressing Enter in the middle of a command, is the same as pressing Enter at
the end of the command (basically you do not need to press End and then
Enter in order to send the command in order to be processed).
Note: These functions try to achieve the same experience as working in the bash terminal, moving freely in a command and modifying the command without rewriting it from the beginning.
Inserting multiple whitespace characters between commands or at the beginning of a command does not affect the resulting command, for example
# The command:
tock$ stop blink
# Will be interpreted as:
tock$ stop blink