Could somebody explain me why pattern in Korn shell (assigned to variable) works this way:u@h:w$ pattern='file_[0-9][0-9]'u@h:w$ ls $patternfile_01  file_02  file_03But it doesn't work for smarter pattern file_{2}([0-9]):$ pattern='file_{2}([0-9])'$ ls $patternls: file_{2}([0-9]): No such file or directory
KSH Pattern from variable does not work
scripting;regular expression;ksh;posix;patterns