Write shell scripts to

(a) Replace blanks with underscores in the names of all files in the current directory.

(b) Rename every file in the current directory by prepending to its namea textual representation of its modification date.

(c) Find all eps files in the file hierarchy below the current directory, and create any corresponding pdf files that are missing or out of date.

(d) Print the names of all files in the file hierarchy below the current directory for which a given predicate evaluates to true. Your (quoted) predicate should be specified on the command line using the syntax of the Unix test command, with one or more at signs (@) standing in for the name of the candidate file.