Chapter 4  -  The UNIX Environment.args.c     -  A program that splits command-line options from arguments.argopt.c   -  An extended version of args.c that flags up illegal options and that expects arguments following some options.environ.c  -  A program that prints out the values of environment variables.showenv.c  -  A program that prints out all the environment variables with their current values.envtime.c  -  A program that prints the low level time value every 2 seconds for 20 seconds.gmtime.c   -  A program that prints human time.ctime.c    -  A program that prints the local time.strftime.c -  A program that gives the user more control over the look of the time output.tmpnam.c   -  A progam that creates a unique temporary file.user.c     -  A program that prints information about the user from password file.hostget.c  -  A program that prints information about the host computer.syslog.c   -  A program that writes message to syslog on error.logmask.c  -  A program that uses logmask to log only messages of a certain priority.  (Needs Linux kernels later than 1.2.11.)limits.c   -  A program that pushes resource to their limits.