问题
Windows command line, I want to search a file for all rows starting with:
# NNN "<file>.inc"
where NNN is a number and <file> any string.
I want to use findstr, because I cannot require that the users of the script install ack.
Here is the expression I came up with:
>findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9_]*.inc" all_pre.txt
The file to search is all_pre.txt.
So far so good. Now I want to pipe that to another command, say for example more.
>findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9]*.inc" all_pre.txt | more
The result of this is the same output as the previous command, but with the file name as prefix for every row (all_pre.txt).
Then comes:
FINDSTR: cannot open |
FINDSTR: cannot open more
Why doesn't the pipe work?
snip of the content of all_pre.txt
# 1 "main.ss"
# 7 "main.ss"
# 11 "main.ss"
# 52 "main.ss"
# 1 "Build_flags.inc"
# 7 "Build_flags.inc"
# 11 "Build_flags.inc"
# 20 "Build_flags.inc"
# 45 "Build_flags.inc(function a called from b)"
EDIT: I need to escape the dot in the regex also. Not the issue, but worth to mention.
>findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9_]*\.inc" all_pre.txt
EDIT after Frank Bollack:
>findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9_]*\.inc.*" all_pre.txt | more
is not working, although (I think) it should look for the same string as before then any character any number of times. That must include the ", right?
回答1:
You are missing a trailing \" in your search pattern.
findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9]*.inc\"" all_pre.txt | more
The above works for me.
Edit:
findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9]*\.inc.*\"" all_pre.txt | more
This updated search string will now match these lines from your example:
# 1 "Build_flags.inc"
# 7 "Build_flags.inc"
# 11 "Build_flags.inc"
# 20 "Build_flags.inc"
# 45 "Build_flags.inc(function a called from b)"
Edit:
To circumvent this "bug" in findstr, you can put your search into a batch file like this:
@findstr /r /c:"^# [0-9][0-9]* \"[a-zA-Z0-9_]*\.inc" %1
Name it something like myfindstr.bat and call it like that:
myfinsdtr all_pre.txt | more
You can now use the pipe and redirection operators as usual.
Hope that helps.
回答2:
I can't really explain the why, but from my experience although findstr behaviour with fixed strings (e.g. /c:"some string") is exactly as desired, regular expressions are a different beast. I routinely use the fixed string search function like so to extract lines from CSV files:
C:\> findstr /C:"literal string" filename.csv > output.csv
No issue there.
But using regular expressions (e.g. /R "^\"some string\"" ) appears to force the findstr output to console and can't be redirected via any means. I tried >, >>, 1> , 2> and all fail when using regular expressions.
My workaround for this is to use findstr as the secondary command. In my case I did this:
C:\> type filename.csv | findstr /R "^\"some string\"" > output.csv
That worked for me without issue directly from a command line, with a very complex regular expression string. In my case I only had to escape the " for it to work. other characters such as , and . worked fine as literals in the expression without escaping.
I confirmed that the behaviour is the same on both windows 2008 and Windows 7.
EDIT: Another variant also apparently works:
C:\> findstr /R "^\"some string\"" < filename.csv > output.csv
it's the same principle as using type, but just using the command line itself to create the pipe.
回答3:
If you use a regex with an even number of double quotes, it works perfectly. But your number of " characters is odd, redirection doesn't work. You can either complete your regex with the second quote (you can use range for this purpose: [\"\"]), or replace your quote character with the dot metacharacter.
It looks like a cmd.exe issue, findstr is not guilty.
来源：https://stackoverflow.com/questions/2737107/piping-findstrs-output