Question: is there a command line utility for changing the color label of files in macosx?

Answer: 
You can write it yourself. Open `/Applications/Utilities/AppleScript Editor.app` and enter the following:

```
on run argv
    tell application "Finder"
        set theFile to POSIX file (item 1 of argv) as alias
        set labelIdx to (item 2 of argv as number)
        set label index of theFile to labelIdx
    end tell
end run

```

Save as `color.scpt` and invoke from Terminal like this:

```
osascript color.scpt somefile.txt 3

```

`somefile.txt` will be colored, `3` is the color: `0` means colorless, 1 through 7 are the Finder's colors (with `1` being red).
Based on the responses here and in referenced posts, I made the following function and added it to my ~/.bash\_profile file:

```
# Set Finder label color
label(){
  if [ $# -lt 2 ]; then
    echo "USAGE: label [0-7] file1 [file2] ..."
    echo "Sets the Finder label (color) for files"
    echo "Default colors:"
    echo " 0  No color"
    echo " 1  Orange"
    echo " 2  Red"
    echo " 3  Yellow"
    echo " 4  Blue"
    echo " 5  Purple"
    echo " 6  Green"
    echo " 7  Gray"
  else
    osascript - "$@" << EOF
    on run argv
        set labelIndex to (item 1 of argv as number)
        repeat with i from 2 to (count of argv)
          tell application "Finder"
              set theFile to POSIX file (item i of argv) as alias
              set label index of theFile to labelIndex
          end tell
        end repeat
    end run
EOF
  fi
}
```
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