Git pre-commit hook to disallow a substring

This took way longer than it should have to figure out, so I wanted to share in case others are trying to do the same thing.

Add this snippet to your Git pre-commit hook to prevent (in this case) the substring FIXME from making it into a committed file. Since the hook includes the substring 'FIXME' you'll need to commit like this:

git add git-hooks/pre-commit
allowfixme=true git commit -m 'Disallow FIXME in committed files.'

Here's the code. Public domain, unless you really need a license, in which case use the MIT license. If you can, I'd appreciate a link, but no worries if not.

# Disallow 'FIXME' from being committed. 'TODO' is for cross-commit notes of
# pending work, but 'FIXME' is for things that need to be updated before
# committing.
# Set allowfixme=true to allow commit anyway, such as if the file contains
# 'FIXME' for a good reason (like this file), or you have some other reason
# to leave it in the repo for now.
if [ "$allowfixme" != "true" ] ; then
  found_fixme=
  for F in $(git diff --cached --name-only) ; do
    C=$(git ls-files -s "$F" | awk '{print $2}')
    if git cat-file blob "$C" | grep -q 'FIXME' ; then
      if [ -z "$found_fixme" ] ; then
        echo "COMMIT REJECTED: Found 'FIXME' in:"
        found_fixme=1
      fi
      echo "  $F"
    fi
  done
  if [ -n "$found_fixme" ] ; then
    echo "Please remove before committing."
    exit 1
  fi
fi

Shell Scripting

One thing that Linux and its brethren have always done well is shell scripting. Windows users are unfortunately missing out on this wonderful tool.

Oh, sure, Windows has DOS .bat and .cmd files, PowerShell scripts, and VBScript .vbs files. That's three different scripting languages to learn, if you want to work with other people (since in a group, someone else is bound to prefer something different than you). Plus, I have an intense dislike of VBScript, mainly for reasons like this:

Const OverwriteExisting = True Set objFSO = CreateObject("Scripting.FileSystemObject") objFSO.CopyFile "C:\file1" , "C:\file2", OverwriteExisting

Three lines to copy a file? Honestly? Anyway, I digress.

Shell scripting may not always be clear, but it does provide powerful tools for doing tasks that would otherwise take forever. Here are a few examples that may help with your media collection:

Rename with Lowercase Extensions

This will rename all files in the current directory and all subdirectories to have lower-case file extensions. It also demonstrates how you may get around the spaces-in-filenames issue that plagues most script writers:

find . -type f | while read name ; do # Get the directory name dname=`dirname "$name"`; # Get the file extension, as it is right now fext=`echo "$name" | sed -e "s/.*\\.\(.*\)/\\1/"`; # Get the file name, without the directory or extension fname=`basename "$name" ".$fext"`; # Make the extension lower-case fext=`echo "$fext" | tr [A-Z] [a-z]`; # Construct the new file name newname=$dname/$fname.$fext; # Rename the old file to the new # The -v option will print each move to the screen mv -v "$name" "$newname" done

Convert All Files to AVI

Here is one example that I use regularly at home. It takes all non-AVI files in this and all subdirectories and makes them into 2-pass encoded XviD AVIs using MEncoder. My wife and I own a DVD player that plays DivX/XviD files, so this makes any videos we may acquire playable on it:

# First, here are some standard options to MEncoder # Use Lame for MP3 encoding, average bitrate of 128 kbps audioOpts="-oac mp3lame -lameopts abr:br=128" # Use XviD for video encoding, bitrate of 750 kbps video1Opts="-ovc xvid -xvidencopts pass=1:bitrate=750" video2Opts="-ovc xvid -xvidencopts pass=2:bitrate=750" find . -type f | while read name ; do # Get the directory name dname=`dirname "$name"`; # Get the file extension, as it is right now fext=`echo "$name" | sed -e "s/.*\\.\(.*\)/\\1/"`; # If the file extension is .avi, no need to do anything if [ "`echo $fext | tr [A-Z] [a-z]`" = "avi" ] ; then echo "*** Skipping '$name', it is an AVI file ***" continue fi # Get the file name, without the directory or extension fname=`basename "$name" ".$fext"`; # Construct the new file name newname=$dname/$fname.avi; echo "*** Converting '$name' to '$newname' ***" # Create a directory to hold temporary data # The '$$' variable expands to the Process ID of # this shell program instance, very useful for # temporary file/directory names mkdir $$ cd $$ # Execute the first pass of mencoder # This generates a log file used by the second pass # That log file is why it needs its own directory # The '&&' at the end will only let the next mencoder # command execute if this one succeeds mencoder "../$name" $audioOpts $video1Opts -o /dev/null && # Execute the second pass of mencoder mencoder "../$name" $audioOpts $video2Opts -o "../$newname" # Go back to the starting directory and clean up cd .. rm -rf $$ done

I hope these are useful. Check back again for other scripting tips.