Open a terminal in Alacritty

Oct 13, 2025 by wbrum.org 26 views

Introduction

The Fish shell is a popular command-line shell known for its simplicity and flexibility. One of its key features is the ability to customize keybindings using the bind command. However, in some cases, the Fish shell may not recognize certain keybindings, even if the escape sequence is correctly captured by showkey -a and bound using the bind command. This article will explore a specific issue where the Fish shell does not recognize the keybinding for Ctrl+Shift+X as a valid keystroke.

Summary

The Fish shell does not recognize the keybinding for Ctrl+Shift+X as a valid keystroke, even though the escape sequence (^[[O) is correctly captured by showkey -a and bound using the bind command. In contrast, the keybinding for Ctrl+Shift+C (escape sequence ^[[Q) works as expected. Both keybindings are declared using similar set and bind commands.

Environment

The following environment was used to reproduce the issue:

Shell: Fish shell (version: fish, version 4.0.0)
Terminal Emulator: Alacritty (version: alacritty 0.15.0-dev (9e9e43d2))

Steps to Reproduce

To reproduce the issue, follow these steps:

Open a terminal in Alacritty: Open a terminal emulator, such as Alacritty, to access the command line.
Start the Fish shell: Start the Fish shell by typing fish in the terminal.
Add keybinding configurations: Add the following keybinding configurations to your Fish configuration file (~/.config/fish/config.fish) or execute them directly in the shell:
```
set command_c \e'[Q'
set command_x \e'[O'
bind $command_c 'echo command_c pressed'
bind $command_x 'echo command_x pressed'
```
Reload the Fish configuration: Reload the Fish configuration by typing source ~/.config/fish/config.fish or restart the shell.
Use showkey -a to confirm escape sequences: Use showkey -a to confirm the escape sequences for the key combinations:
- Press Ctrl+Shift+C → showkey -a outputs ^[[Q
- Press Ctrl+Shift+X → showkey -a outputs ^[[O
Test the keybindings in Fish: Test the keybindings in Fish by pressing Ctrl+Shift+C and Ctrl+Shift+X.

Expected Behavior

The expected behavior is that pressing Ctrl+Shift+C should output: command_c pressed and pressing Ctrl+Shift+X should output: command_x pressed.

Actual Behavior

However, the actual behavior is that pressing Ctrl+Shift+C works as expected and outputs: command_c pressed, but pressing Ctrl+Shift+X does not trigger the bound command (command_x pressed) and appears to be ignored by Fish.

Investigation

To investigate this issue, we can try to reproduce it in a different environment. We can also try to use different keybindings and see if the issue persists.

Possible Causes

There are several possible causes for this issue:

Fish shell version: The issue may be specific to the Fish shell version 4.0.0.
Terminal emulator: The issue may be related to the Alacritty terminal emulator.
Keybinding configuration: The issue may be caused by the specific keybinding configuration used.

Workarounds

To work around this issue, we can try the following:

Use a different keybinding: Try using a different keybinding, such as Ctrl+Shift+V, and see if the issue persists.
Use a different terminal emulator: Try using a different terminal emulator, such as xterm, and see if the issue persists.
Update Fish shell version: Try updating the Fish shell version to a newer version and see if the issue is resolved.

Conclusion

Q: What is the issue with the Fish shell keybinding for `Ctrl+Shift+X`?

A: The Fish shell does not recognize the keybinding for Ctrl+Shift+X as a valid keystroke, even though the escape sequence (^[[O) is correctly captured by showkey -a and bound using the bind command.

Q: What are the steps to reproduce the issue?

A: To reproduce the issue, follow these steps:

Open a terminal in Alacritty.
Start the Fish shell.
Add the following keybinding configurations to your Fish configuration file (~/.config/fish/config.fish) or execute them directly in the shell:
```
set command_c \e'[Q'
set command_x \e'[O'
bind $command_c 'echo command_c pressed'
bind $command_x 'echo command_x pressed'
```
Reload the Fish configuration (source ~/.config/fish/config.fish) or restart the shell.
Use showkey -a to confirm the escape sequences for the key combinations:
- Press Ctrl+Shift+C → showkey -a outputs ^[[Q
- Press Ctrl+Shift+X → showkey -a outputs ^[[O
Test the keybindings in Fish:
- Press Ctrl+Shift+C
- Press Ctrl+Shift+X

Q: What is the expected behavior?

A: The expected behavior is that pressing Ctrl+Shift+C should output: command_c pressed and pressing Ctrl+Shift+X should output: command_x pressed.

Q: What is the actual behavior?

A: The actual behavior is that pressing Ctrl+Shift+C works as expected and outputs: command_c pressed, but pressing Ctrl+Shift+X does not trigger the bound command (command_x pressed) and appears to be ignored by Fish.

Q: What are the possible causes of this issue?

A: There are several possible causes for this issue:

Fish shell version: The issue may be specific to the Fish shell version 4.0.0.
Terminal emulator: The issue may be related to the Alacritty terminal emulator.
Keybinding configuration: The issue may be caused by the specific keybinding configuration used.

Q: What are the workarounds for this issue?

A: To work around this issue, we can try the following:

Use a different keybinding: Try using a different keybinding, such as Ctrl+Shift+V, and see if the issue persists.
Use a different terminal emulator: Try using a different terminal emulator, such as xterm, and see if the issue persists.
Update Fish shell version: Try updating the Fish shell version to a newer version and see if the issue is resolved.

Q: Is this issue specific to the Fish shell?

A: No, this issue is not specific to the Fish shell. Similar issues may occur in other shells, such as Bash or Zsh.

Q: Can I report this issue to the Fish shell developers?

A: Yes, you can report this issue to the Fish shell developers using the official issue tracker on GitHub.

Q: How can I get help with this issue?

A: You can get help with this issue by asking on the Fish shell community forum or by seeking help from a Fish shell expert.