Tred output to file?

Help
1

Hi, I’m trying to figure out why tred won’t output to my file (using Windows). I’m not sure if this is a problem with tred or if I just don’t understand Powershell, but based on what I’m reading I should be able to simply output stdin with >

In Powershell,
dot -Tsvg file.dot -o file.svg
Works fine and creates a nice pretty svg output, and
tred file.dot
Outputs with nice reformatting to Powershell via stdin without complaint as well, however,
tred file.dot > file_tred.dot
Also runs, but then,
dot -Tsvg file_tred.dot -o file.svg
Gives me the following error,
Error: file_tred.dot: syntax error in line 1 near ’ ■d’

Are there some sort of junk characters I need to discard before piping tred to a file, or is something else going on? I tried to run tred with -Tdot and/or -o like dot, but it doesn’t seem to like anything other than the flags to print to stderr.

If anyone can explain to me what I’m doing wrong I’d appreciate it.

2

My guess is that Powershell puts a BOM in your file. See Syntax error in line 1 - #3 by magjac.

3

Thanks for the reply. I’m not sure why it’s in there since the file shows up as UTF-8 without BOM in N++, but for now my workaround is just to delete the file, recreate it, run tred without piping the output, copy/paste the output from Powershell, then run the second command. Still gets the job done.

4

There’s already an action in graphviz cgraph/scan.l that ignores UTF-8 BOM symbols.

"\xEF\xBB\xBF" /* ignore BOM */

north@margil cgraph % git blame -L197,197 scan.l
5afd378187 (Emden R. Gansner 2014-01-24 11:46:26 -0500 197) "\xEF\xBB\xBF"                              /* ignore BOM */
north@margil cgraph %

This has been there for a long time.

This appears to be correct, according to Byte order mark - Globalization | Microsoft Learn

5

We could probably add an option to tred to output to a file. Please open a Gitlab issue for this if you think it would be helpful.

6

powershell could be adding a utf 16 bom? If you can attach the output we can see

7

For anyone pondering the same, here is the decoding of the error the OP posted:

’              |       | ■              | d    | ’
0xe2 0x80 0x99 | 0x20  | 0xe2 0x96 0xa0 | 0x64 | 0xe2 0x80 0x99
right quote    | space | black square   | d    | right quote

I have no theories, but Windows does like BOMs, Unicode is harder than you think · mcilloni's blog

8

In my limited exposure to Powershell, it is full of side-effects and surprises.