How can I add OS X “tags” to files programmatically?

Question

Since Mavericks, OS X has had the ability to tag & colour files in Finder.

Is there any

Answer 1

This does not cover tags, but for changing label colors, one way to do it is through a command like this:

xattr -wx com.apple.FinderInfo \
0000000000000000000400000000000000000000000000000000000000000000 myfile.txt

The 04 buried in the middle is setting the file color.

Here is a python script which wraps that command lets you set the tag color on a file or series of files:

import sys
import subprocess

def colorizeFile(ColorName,FileName):
    ReverseTable = {
         "clear"  :  "01",
         "gray"   :  "03",
         "green"  :  "04",
         "purple" :  "06",
         "blue"   :  "09",
         "yellow" :  "0A",
         "red"    :  "0C",
         "orange" :  "0E",
         "c"      :  "01",
         "a"      :  "03",
         "g"      :  "04",
         "p"      :  "06",
         "b"      :  "09",
         "y"      :  "0A",
         "r"      :  "0C",
         "o"      :  "0E",
    }

    HexString = 18*"0" + ReverseTable.get(ColorName) + 44*"0"
    Xcommand = 'xattr -wx com.apple.FinderInfo {0} {1}'.format(HexString,FileName)
    ProcString = subprocess.check_call(Xcommand, stderr=subprocess.STDOUT,shell=True) 

if __name__ == "__main__":
    if len(sys.argv)<3:
        sys.stderr.write(__doc__.format(sys.argv[0]))
    else:
        Cname = sys.argv[1]
        Flist = sys.argv[2:]
        for File in Flist:
            colorizeFile(Cname.lower(),File)
        sys.stderr.write("## Colorized {0} file(s) as {1}\n".format(len(Flist),Cname)) 

Usage is:

  labelcolor.py [color] *.jpg

where [color] is a name or abbreviation as defined below:

    clear (c), grAy (a), green (g), purple (p), 
    blue (b), yellow (y), red (r), orange (o)