Library Functions Summary (The GNU Awk User’s Guide)

Reading programs is an excellent way to learn Good Programming. The functions and programs provided in this chapter and the next are intended to serve that purpose.
When writing general-purpose library functions, put some thought into how to name any global variables so that they won’t conflict with variables from a user’s program.
The functions presented here fit into the following categories: General problems Number-to-string conversion, testing assertions, rounding, random number generation, converting characters to numbers, joining strings, getting easily usable time-of-day information, and reading a whole file in one shot Managing data files Noting data file boundaries, rereading the current file, checking for readable files, checking for zero-length files, and treating assignments as file names Processing command-line options An awk version of the standard C getopt() function Reading the user and group databases Two sets of routines that parallel the C library versions Traversing arrays of arrays Two functions that traverse an array of arrays to any depth