Alias fails with unprotected ^ in %$

[vefatica]

What's happening below and how fo I fix it?

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo %$]`

v:\> myecho ^e[
TCC: Syntax error "@len[^e["

 

[Alpengreis]

Same here ... hmm ... will investigate a bit time here ...

 

[Alpengreis]

It seems, ALIAS tries to execute the ANSI sequence (in contrary to the "normal" @len function). So if I escape the square bracket, myecho alias executes it.

myecho ^e^[

It produces a blank line.

 

[vefatica]

I think it's ECHO that escapes the [.

But why is there an error in the first place?

 

[vefatica]

It only seems to happen when there are multiple occurrences of %$ in the alias definition, one being in a function.

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo %$]`

v:\> myecho ^e[92mfoo
TCC: Syntax error "@len[^e[92mfoo"

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo bar]`

v:\> myecho ^e[92mfoo
TCC: Syntax error "@len[^e[92mfoo"

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo bar,echo bar]`

v:\> myecho ^e[92mfoo
bar

 

[Alpengreis]

I think it's ECHO that escapes the [.

View attachment 4938

Yes, after your example I think that too.

 

[Alpengreis]

It only seems to happen when there are multiple occurrences of %$ in the alias definition, one being in a function.

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo %$]`

v:\> myecho ^e[92mfoo
TCC: Syntax error "@len[^e[92mfoo"

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo bar]`

v:\> myecho ^e[92mfoo
TCC: Syntax error "@len[^e[92mfoo"

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo bar,echo bar]`

v:\> myecho ^e[92mfoo
bar

Oh, that's very interesting and good "debugged"!

That's not WAD probably!

 

[vefatica]

And IF works better that @IF.

v:\> alias myecho `%@if[%@len[%$] LT 1000,echo %$,echo %$]`

v:\> myecho ^e[92mfoo
TCC: Syntax error "@len[^e[92mfoo"

v:\> alias myecho `if %@len[%$] LT 1000 (echo %$) else (echo %$)`

v:\> myecho ^e[92mfoo
foo

 

[rconn]

Same problem as in your other thread; the nested variable expansion doesn't like your unprotected / unmatched '[' characters.

 

[vefatica]

It's OK. IF, instead of @IF works fine.

But I still don't really understand the problem. Why is it not a problem here? Is it peculiar to %$?

v:\> set z=[

v:\> alias myecho `echo %@if[%@len[%z] NE 0,%z,%z]`

v:\> myecho
[

 

[vefatica]

So what's the difference between these? They're the same except that the first uses %$ inside %IF and the second uses %z?

v:\> alias myecho `set z=%$ & %@if[%@len[%$] NE 0,echo %$,echo %$]`

v:\> myecho [
TCC: Syntax error "@len[["

v:\> alias myecho `set z=%$ & %@if[%@len[%z] NE 0,echo %z,echo %z]`

v:\> myecho [
[

 

[rconn]

So what's the difference between these? They're the same except that the first uses %$ inside %IF and the second uses %z?

v:\> alias myecho `set z=%$ & %@if[%@len[%$] NE 0,echo %$,echo %$]`

v:\> myecho [
TCC: Syntax error "@len[["

v:\> alias myecho `set z=%$ & %@if[%@len[%z] NE 0,echo %z,echo %z]`

v:\> myecho [
[

The %$ is an alias variable, and is expanded during alias expansion. The %z is an environment variable, and is expanded during variable expansion (which occurs later).

 

[vefatica]

Uncle!