regex_replace template transformation outputs literal template string

[josephschmitt]

Description

The regex_replace template transformation documented at https://alexpasmantier.github.io/television/advanced/template-system/ does not seem to work. Instead of applying the regex replacement, television outputs the raw template string as a literal.

Other transformations (strip_ansi, split, piping them together) all work correctly. Only regex_replace appears broken.

Example

Minimal custom channel (~/.config/television/cable/test.toml):

[metadata]
name = "test"

[source]
command = "echo 'hello world'"
output = "{regex_replace:\\s+:_}"

Open with tv test, select an entry.

Expected:

tv test
hello_world

Actual:

tv test
{regex_replace:\s+:_}

I also tried these variations, all with the same result:

• {strip_ansi|split: :1|regex_replace:^~:@}
• {regex_replace:^~:$HOME}
• {regex_replace:hello:goodbye}

Expected behavior

regex_replace should apply the regex substitution to the entry. For example, {regex_replace:\\s+:_} on hello world should output hello_world.

Actual behavior

The literal template string is output instead (e.g., {regex_replace:\\s+:_}).

Environment

• OS: macOS (Darwin 24.6.0, arm64)
• TV version: 0.15.2
• Shell: fish
• Terminal: ghostty (inside tmux)
• Config: default ~/.config/television/config.toml
• Channel: custom channel (shown above)

Additional context

I was trying to use regex_replace in the output field of a custom channel to expand ~ back to $HOME for paths that are display-shortened. The workaround for now is to avoid regex_replace and handle the transformation externally.

[lalvarezt]

Hi, creator of string_pipeline here. Try

replace:s/PATTERN/REPLACEMENT

[josephschmitt]

Hi, creator of string_pipeline here. Try

replace:s/PATTERN/REPLACEMENT

@lalvarezt that seems to be a no-op (vs just printing out the whole template). here’s my test toml I tried:

[metadata]
name = "test"

[source]
command = "echo 'hello world'"
output = "{replace:s/\\s/_}"

When I run tv test it outputs the unchanged hello world instead of the expected hello_world. I even tried with a simpler pure character replacement of output = "{replace:s/h/_}" and still I get no replacement.

[lalvarezt]

Hi there,

I made a typo on the previous message the correct syntax is

Syntax: replace:s/PATTERN/REPLACEMENT/FLAGS

Parameter	Type	Required	Description
PATTERN	regex	✅	Regular expression to find
REPLACEMENT	string	✅	Text to replace matches with
FLAGS	string	❌	Modifiers: g (global), i (case-insensitive), m (multiline), s (dot-all)

doc here

so your example would be (notice the final /)

[metadata]
name = "test"

[source]
command = "echo 'hello world'"
output = "{replace:s/\\s/_/}"

[josephschmitt]

@lalvarezt still not working, copy/pasted your correction above just to be sure and I still get hello world in the picker. Even tried adding a g flag

[lalvarezt]

that's not what output does, select it and you'll see, what you want is display

output: formats the selected value
display: formats the value you see in tv

[metadata]
name = "test"

[source]
command = "echo 'hello world'"
output = "{replace:s/\\s/_/}"
display = "{replace:s/\\s/_/}"

[josephschmitt]

@lalvarezt the other example from the docs isn’t working either

[josephschmitt]

@lalvarezt ah, let me try!

[josephschmitt]

@lalvarezt ok so I think this is working with the closing / and using replace instead of regex_replace! Should we update the docs from https://alexpasmantier.github.io/television/advanced/template-system/#replace-with-regex ? That’s still saying to use {regex_replace:pattern:replacement}

[lalvarezt]

@lalvarezt ok so I think this is working with the closing / and using replace instead of regex_replace! Should we update the docs from https://alexpasmantier.github.io/television/advanced/template-system/#replace-with-regex ? That’s still saying to use {regex_replace:pattern:replacement}

yup, that's true, the doc is not correct

[josephschmitt]

@lalvarezt one last question, appreciate all your help. I originally ran into this issue when trying to add this cable channel: #902. I’m trying to expand ~ to $HOME. My original implementation was just using sed since I couldn’t get the template replacement working. I tried using the working syntax, but it seems like it just replaces with empty string. Is the templating system not able to read/resolve $HOME? Do you think I should stick with sed in that case?

[lalvarezt]

yes, that's not something that's currently implemented unfortunately. I made some changes string_pipeline v0.13.0 (the one that tv uses) but it's not quite there yet. There are a lot of edge cases and syntax variations, something for the future

[josephschmitt]

@lalvarezt I'll stick with sed then, thanks!