# Current REPL number
**URL:** https://discourse.julialang.org/t/current-repl-number/76240
**Category:** General Usage
**Tags:** repl
**Created:** [February 11, 2022, 11:26am UTC](https://discourse.julialang.org/t/current-repl-number/76240 "2022-02-11T11:26:50Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [February 11, 2022, 11:26am UTC](https://discourse.julialang.org/t/current-repl-number/76240/1 "2022-02-11T11:26:50Z")
Does Julia provide an API for extracting the current REPL number?
By “current REPL number”, I mean the `x` in `REPL[x]` in error messages like the following:
```julia
julia> error()
ERROR:
Stacktrace:
[1] error()
@ Base ./error.jl:42
[2] top-level scope
@ REPL[1]:1
```
---
### Author:  [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)
#### Post date: [February 11, 2022, 11:53am UTC](https://discourse.julialang.org/t/current-repl-number/76240/2 "2022-02-11T11:53:37Z")
`@ __FILE__ ` in the REPL.
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [February 11, 2022, 11:56am UTC](https://discourse.julialang.org/t/current-repl-number/76240/3 "2022-02-11T11:56:28Z")
Ok, but I’m looking for something which works also in library code.
---
### Author:  [@rfourquet](https://discourse.julialang.org/u/rfourquet)
#### Post date: [February 11, 2022, 12:32pm UTC](https://discourse.julialang.org/t/current-repl-number/76240/4 "2022-02-11T12:32:43Z")
I use this to set my repl prompt in startup.jl:
```julia
function repl_line()
hist = Base.active_repl.interface.modes[1].hist
hist.cur_idx - hist.start_idx
end
```
(or actually, `repl.interface.modes[1].hist` if i get a handle on `repl` from `atreplinit`)
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [February 11, 2022, 12:59pm UTC](https://discourse.julialang.org/t/current-repl-number/76240/6 "2022-02-11T12:59:18Z")
This is close to what I want, but it seems to have some quirks:
```julia
_ _ _(_)_ | Documentation: https://docs.julialang.org
(_) | (_) (_) |
_ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
| | | | | | |/ _' | |
| | |_| | | | (_| | | Version 1.7.2 (2022-02-06)
_/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |
julia> function repl_line()
hist = Base.active_repl.interface.modes[1].hist
hist.cur_idx - hist.start_idx
end;
julia> repl_line()
0 # Would have expected this to be 2, but fine
julia> repl_line()
2 # Why does it jump by 2 now?
julia> repl_line()
2 # No increment, presumably because same input
julia> exp(1); # Dummy input
julia> repl_line()
2 # Still same?!
julia> repl_line()
4 # Jumping by 2 again
```
---
### Author:  [@rfourquet](https://discourse.julialang.org/u/rfourquet)
#### Post date: [February 11, 2022, 1:15pm UTC](https://discourse.julialang.org/t/current-repl-number/76240/7 "2022-02-11T13:15:32Z")
> [@ettersi](#):
>
> ```julia
> function repl_line()
> hist = Base.active_repl.interface.modes[1].hist
> hist.cur_idx - hist.start_idx
> end
>
> ```
Yes this is tricky, this is because you used something like uparrow or Ctrl-p to go back to previous history entries, this is how the REPL works. For example, the first `repl_line()` call shows 0: this is presumably because you used uparrow instead of actually typing `repl_line()`, and then `repl_line()` was the last thing typed in the previous julia session.
The alternative is to use: `length(hist.history) + 1 - hist.start_idx` (which i actually also show in my REPL prompt when it differs from the `repl_line()` above, so e.g. my prompt shows `0/2>` for your first `repl_line()` example if i pressed uparrow).
---
### Author:  [@ettersi](https://discourse.julialang.org/u/ettersi)
#### Post date: [February 11, 2022, 1:22pm UTC](https://discourse.julialang.org/t/current-repl-number/76240/9 "2022-02-11T13:22:44Z")
Better, but still not perfect 😢
```julia
_ _ _(_)_ | Documentation: https://docs.julialang.org
(_) | (_) (_) |
_ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
| | | | | | |/ _' | |
| | |_| | | | (_| | | Version 1.7.2 (2022-02-06)
_/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |
julia> function repl_line()
hist = Base.active_repl.interface.modes[1].hist
length(hist.history) + 1 - hist.start_idx
end;
julia> repl_line()
2
julia> repl_line()
2 # Still no update for ctrl+up inputs
julia> exp(1); # Dummy input
julia> repl_line()
4 # But at least immediate updates
```
Thanks for your help anyway, much appreciated! ❤