batch: FINDSTR regular expression not work

Question

echo a.txt| FINDSTR /R ".+\.txt$"

not work and not even:

echo a.txt| FINDSTR /R .+\.txt$

Why?

Edit:

Now works!

echo a.txt| FINDSTR /R ..*\.txt$

Open a Command Prompt and enter`FindStr /?`, then read the usage information! — Compo, Dec 06 '18 at 00:07
Why? Because you failed to read the help file for the `FINDSTR` command first. — Squashman, Dec 06 '18 at 01:54
We can't know that "not works" means, unless you explain what you want to achieve! — aschipfl, Dec 06 '18 at 10:03

Thomas Weller · Accepted Answer · 2018-12-06T13:01:58.413

4

a) There is no + in the regex of Findstr. Use * instead. ..* should be the correct replacement for .+.

b) There can be invisible character before the end of the line, e.g. caused by echo if there's a trailing space before |. Add another . before the line end to cover that.

C:\> echo a.txt | findstr /r ".*\.txt.$"
a.txt

It's also possible without the quotation marks.

edited Dec 06 '18 at 13:01

answered Dec 05 '18 at 23:54

Thomas Weller

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3

@ThomasWeller The invisible character is the space between `a.txt` and `|` which is also output by `echo` and therefore redirected to handle __STDIN__ of command `findstr`. Everything is as expected on using `echo a.txt| findstr /R ".*\.txt$"`. See for example my answer on [Why does ECHO command print some extra trailing space into the file?](https://stackoverflow.com/a/46972524/3074564) for details. – Mofi Dec 06 '18 at 06:55
3

Changing `+` to `*` changes the behaviour; rather replace `.+` by `..*` to achieve the same result... – aschipfl Dec 06 '18 at 10:02
@aschipfl: great suggestion. I added this into the answer – Thomas Weller Dec 06 '18 at 13:02

batch: FINDSTR regular expression not work

1 Answers1