__bsd_ls_shim.bash

# While GNU coreutil's ls is generally more featureful (including colorization
# based on file extensions, SI size formats, ISO date and time formats,
# semantic version sort, etc.), OS X's fork of FreeBSD ls allows viewing HFS+
# extended attributes and access control lists through the -@ and -e flags,
# respectively.
#
# This script provides a shim to allow BSD ls to be invoked with GNU-style
# flags and .dircolor files, and a function that shadows ls, invoking coreutils
# ls by default but automatically switching to the shim when the -@ and/or -e
# flags are detected.
#
# Paste into your .bashrc after `eval $(dircolors ~/.dircolors)` and before
# any ls aliases.

if [[ "$OSTYPE" == darwin* ]]; then
    # Look for an alternate ls in the $PATH
    __bsd_ls=/bin/ls
    __gnu_ls=$(which gls || which ls)
    if [[ "$__gnu_ls" == "$__bsd_ls" ]]; then unset __gnu_ls; fi
    if [[ "$__gnu_ls" ]]; then
        if [[ ! $LS_COLORS ]]; then
            eval $($(which gdircolors || which dircolors))
        fi
        # Generate fallback colors for BSD ls
        export LSCOLORS=$(python - <<'EOD'
import os, sys
types=['di','ln','so','pi','ex','bd','cd','su','sg','tw','ow']
LS_COLORS=[e.split('=') for e in os.environ['LS_COLORS'].split(':') if len(e) > 0]
LS_COLORS={e[0]:e[1] for e in LS_COLORS if e[0]=='no' or e[0] in types}
LS_COLORS={k:[int(e) for e in v.split(';') if e] for k,v in LS_COLORS.items()}
LS_COLORS=[LS_COLORS.get('no',[])+LS_COLORS.get(k,[]) for k in types]
LSCOLORS=[]
for entry in LS_COLORS:
    fgcodes=[code for code in entry if (code/10 == 3 or code/10 == 9)]
    fgcolor=chr(fgcodes[-1]%10+ord('a')) if fgcodes else 'x'
    brcodes=[code for code in entry if code in [0,1,2,21,22]]
    bright=((brcodes and brcodes[-1]==1) or (fgcodes and fgcodes[-1]/10==9))
    fgcolor=fgcolor.upper() if bright else fgcolor
    bgcodes=[code for code in entry if (code/10 == 4 or code/10 == 10)]
    bgcolor=chr(bgcodes[-1]%10+ord('a')) if bgcodes else 'x'
    LSCOLORS.append(fgcolor)
    LSCOLORS.append(bgcolor)
sys.stdout.write(''.join(LSCOLORS))
EOD
)
        fi # [[ $LS_COLORS ]]
        function __bsd_ls_shim {
            # An abstraction layer to allow calling BSD ls with a subset
            # of the GNU ls style parameters, and gracefully handle errors.
            python - "$__bsd_ls" "$BASH_SOURCE" $FUNCNAME $@ <<'EOD'
# coding=UTF-8
import os, sys, subprocess
__bsd_ls=sys.argv[1]
BASH_SOURCE=sys.argv[2]
FUNCNAME=sys.argv[3]
lookup = {'--all':'a','a':'a','--almost-all':'A','A':'A',
          '--format=single-column':'1','1':'1','--format=vertical':'C',
          'C':'C','--format=horizontal':'x','--format=across':'x','x':'x',
          '--format=commas':'m','m':'m','--format=verbose':'l',
          '--format=long':'l','l':'l','--sort=size':'S','S':'S',
          '--sort=time':'t','t':'t','--reverse':'r','r':'r','--inode':'i',
          'i':'i','--size':'s','s':'s','o':'o','g':'g',
          '--numeric-uid-gid':'n','n':'n','--human-readable':'h','h':'h',
          '--full-time':'T','--time=use':'u','--time=access':'u',
          '--time=atime':'u','u':'u','--time=ctime':'c','--time=status':'c',
          'c':'c','--indicator-style=classify':'F','--classify':'F','F':'F',
          '--indicator-style=slash':'p','p':'p','--dereference':'L','L':'L',
          '--dereference-command-line':'H','H':'H','--recursive':'R','R':'R',
          '@':'@','e':'e','--hide-control-chars':'q','q':'q','--escape':'b',
          'b':'b','--directory':'d','d':'d','f':'f'}

in_flags=[]
misc_args=[]
for arg in sys.argv[4:]:
    if arg.startswith('--'):
        in_flags.append(arg)
    elif arg.startswith('-'):
        in_flags.extend(list(arg)[1:])
    else:
        misc_args.append(arg)

color_flag=None
out_flags=[]
err_flags=[]
for flag in in_flags:
    if flag.startswith('--color'):
        color_flag=flag
    elif flag=='f':
        color_flag=flag
        out_flags = [flag for flag in out_flags
                     if flag not in ['l','s']]+['f']
    else:
        try:
            out_flags.append(lookup[flag])
        except:
            err_flags.append(flag)
out_flags=['-'+''.join(out_flags)] if out_flags else []

if err_flags:
    err_flags=' '.join(['-'+flag if len(flag)==1 else flag for flag in err_flags])
    print('The following flags were not passed to '+__bsd_ls+' by '+FUNCNAME)
    print('in '+BASH_SOURCE+': '+err_flags)

# The BSD ls flag -G is equivalent to GNU ls flag --color=auto, but we can
# more precisely match the GNU --color flag with environment variables.
if (not color_flag or
        color_flag == 'f' or
        color_flag == '--color=never' or
        color_flag == '--color=no' or
        color_flag == '--color=none'):
    os.environ.pop('CLICOLOR',None)
    os.environ.pop('CLICOLOR_FORCE',None)
elif (color_flag == '--color=auto' or
      color_flag == '--color=tty' or
      color_flag == '--color=if-tty'):
    os.environ['CLICOLOR']='1'
    os.environ.pop('CLICOLOR_FORCE',None)
elif (color_flag == '--color' or
      color_flag == '--color=always' or
      color_flag == '--color=yes' or
      color_flag == '--color=force'):
    os.environ['CLICOLOR']='1'
    os.environ['CLICOLOR_FORCE']='1'
else:
    print('error in '+BASH_SOURCE+' function '+FUNCNAME+':')
    # This error message is copied verbatim from GNU ls
    print('invalid argument ‘'+color_flag[8:]+'’ for ‘--color’')
    print('Valid arguments are:')
    print('  - ‘always’, ‘yes’, ‘force’')
    print('  - ‘never’, ‘no’, ‘none’')
    print('  - ‘auto’, ‘tty’, ‘if-tty’')
    exit(1)

# subprocess.Popen() is safe against command injection when shell=False
exit(subprocess.Popen(args=[__bsd_ls]+out_flags+misc_args,
                     shell=False,
                       env=os.environ).wait())
EOD
        }
        function ls {
            # regex to match the -@ and -e parameters
            if [[ ! "$__gnu_ls" || "$@" =~ (^|[[:space:]])-[[:alnum:]]*[@e] ]]; then
                __bsd_ls_shim $@
            else
                "$__gnu_ls" $@
            fi
        }
    fi # [[ $__gnu_ls ]]
fi