Tuesday, May 5, 2009

gnu find and grep: using path patterns to match more than one file extension

Example using Cygwin gnu find, xargs and grep to search for a typo in XSLT and XML files. Note that -iregex matches a pattern in the whole path, and the pattern is a POSIX basic regex:

C:\>find ./ -iregex '.*\.\(xslt\^|xml\)' -type f -print | xargs grep -i "staus"

When find matches a file path, the path is piped to xargs, which hands it off to grep to search for the string "staus" - which I want to replace with "status" (but not here :).

Monday, May 4, 2009

Cygwin setup.exe fails during upgrade

Like Ruben, who provided the clues, I discovered that a corrupt/incompatible alternatives.lst.bz file in the C:\cygwin\etc\setup directory caused Cywin setup.exe to fail.

A few clues pointed to this file as the culprit:

  1. First time through, the installer complained that some other Cygwin process had locked the readme file

  2. the installer just looped indefinitely on extracting the README file from alternatives.lst.bz until I killed it

  3. The only .bz file in C:\cygwin\etc\setup with today's date was alternatives.lst.bz.

Here's what the log file recorded, for several thousand lines:

2009/05/04 11:01:23 io_stream_cygfile:
fopen(/etc/alternatives/README) failed 13 Permission denied
2009/05/04 11:01:23 Failed to open
cygfile:///etc/alternatives/README for writing.

I renamed the file to alternatives.lst.bz.bak , then reran setup.exe to successfully upgrade Cygwin.

Now I suppose I should log a bug report...

How to fix apropos for Cygwin

If the apropos command in Cygwin doesn't find anything expected, run /usr/sbin/makewhatis from your Cygwin bash prompt to rebuild the whatis database.

Thanks to Mike and Igor for their tips.

Friday, May 1, 2009

How to make Windows %path% readable

If like me your Windows %path% looks something like this:

Python26Libidlelib;C:cygwinbin;C:Program FilesWindows 
Resource KitsTools;C:WINDOWSsystem32;C:WINDOWS;C:WINDOWS
Downloaded ProgramFiles;C:Program FilesIBMDirectorbin;C:
Program FilesDiskeeper CorporationDiskeeper;c:Program 
FilesMicrosoft SQL Server90Toolsbinn;C:Program Files
Rationalcommon;c:scripts;C:Program FilesjEdit;C:Program 
FilesQuickTimeQTSystem;C:Program FilesTortoiseSVNbin;C:
ipdsdevaxis2axis2c-rel-1.3.0lib;C:Program FilesJava

Then save this to "road.bat" somewhere on your path:

@echo off
rem source: http://www.perlmonks.org/?node_id=757655
for %%i in ("%path:;=" "%") do @echo %%i

When you run C:\>road all those paths are nicely split and one-lined:

and you can do cool things like C:\>road | find /i "Perl" to find out where Perl is hiding.

To paraphrase the (brilliant) author VinsWorldcom, this one-liner

wraps the %PATH% ENV var in double quotes and then replaces all the semicolon separators with a double-quote, space, double quote. This effectively puts double quotes around all the paths (so spaces won't give any troubles) then use the for loop to list each newly double-quoted string.