question: long freeSpaceUnix ( String path , boolean kb , boolean posix , long timeout ) throws IOException { if ( path . length ( ) == 0 ) { throw new IllegalArgumentException ( "Path must not be empty" ) ; } String flags = "-" ; if ( kb ) { flags += "k" ; } if ( posix ) { flags += "P" ; } String [ ] cmdAttribs = flags . length ( ) > 1 ? new String [ ] { DF , flags , path } : new String [ ] { DF , path } ; List < String > lines = performCommand ( cmdAttribs , 3 , timeout ) ; if ( lines . size ( ) < 2 ) { throw new IOException ( "Command line '" + DF + "' did not return info as expected " + "for path '" + path + "'- response was " + lines ) ; } String line2 = lines . get ( 1 ) ; StringTokenizer tok = new StringTokenizer ( line2 , " " ) ; if ( tok . countTokens ( ) < 4 ) { if ( tok . countTokens ( ) == 1 && lines . size ( ) >= 3 ) { String line3 = lines . get ( 2 ) ; tok = new StringTokenizer ( line3 , " " ) ; } else { throw new IOException ( "Command line '" + DF + "' did not return data as expected " + "for path '" + path + "'- check path is valid" ) ; } } else { tok . nextToken ( ) ; } tok . nextToken ( ) ; tok . nextToken ( ) ; String freeSpace = tok . nextToken ( ) ; return parseBytes ( freeSpace , path ) ; }
target:  Find free space on the *nix platform using the 'df' command.