Shell Programming and Scripting

If you are looking for a way to format the current date and time in a particular way, pravin27 already showed you how to use the date utility to do that. (And, as linuxrulez suggested, we assume that when posting in the Shell Programming and Scripting forum, you already know how to use the man utility to find out how the arguments to a utility [such as date] will be processed on your system.) But, using the term extract to describe this would be strange.

If you are looking for a way to extract the date and time from a file that contains the text you showed us in the 1st posting in this thread, the date utility is not going to help. And, although you could invoke the cut utility twice to remove the unwanted [ and ] characters, the single invocation of sed as suggested by linuxrulez would be much more efficient.

If what you have is a shell variable containing your sample input and you want to get rid of those unwanted characters in the contents of the variable, try the following:

Code:

var="[Tue Oct  1 13:32:40 2013]" # set var to your sample value
var="${var#[[]}" # remove leading "["
var="${var%[]]}" # remove trailing "]"
printf "%s\n" "$var" # print the updated value

which will work in any shell that performs the basic parameter expansions specified by the POSIX standards and the Single UNIX Specifications.

If this is a homework assignment (and the assignment is to use cut and date to remove the leading and trailing characters from a line in a file or from a variable), you know that home work assignments can only be posted in the Homework and Coursework Questions forum and that you need to include details about your class and homework assignment in any requests to get help doing your homework.