6. checking status of print job (lpq -Pmajors)

Use the command 'lpq -Pmajors' to check the status of Majors lab printer.

7. remove job from print queue (lprm -Pmajors)

If you send a job to the printer but then decide you don't want it to be printed on the majors lab laser printer. The command 'lprm' (no quotes) will allow you to purge the job. There are two methods of purging a job:

• To purge all jobs under your loginid, use the command

• To purge a specific job, you must first determine the "print job number" and then specify the job number on the lprm command. The job number can be determined by using the lpq command. Here is the sequence:

lprm -Pmajors <jobid> Specify the job id as shown. This will
cause only the job specified to be
purged.

8. e-mail (pine, reading messages, composing messages)

Use the command 'pine' to read email (a message tells you that you have received mail when you login). After typing this command, "pine" will enter you into an interactive, menu-driven mailer. After reading your mail, you can save it, reply, delete it, and a variety of other functions.
See the pine man page for full details.

9. editor (pico)

• Pico is one of the simplest editors to learn.

• Use the command 'pico <filename>' to start pico.

• Type in the characters you wish in the file.

• Examine the ^ commands at the bottom of the window.

• Use the arrow keys to position the cursor.

10. list files (ls)

• Use the command 'ls' to list the contents of current directory.

To list the contents of another directory, you can either "cd" to it
and type "ls", or you can simply supply the directory name as an argument.
For example: "ls /etc", would list the contents of the directory /etc.

• Use command 'ls -al' to list all file with detailed attributes.

• Use the command 'ls -F' to list files with a single character attribute.

11. remove files (rm)

Use the command 'rm <file>' to remove the file <file>.

By default, it does not ask for conformation before wiping out exactly
what you tell it to. For example, this command would erase all files
ending in `.o', and `.out':

rm *.o *.out

But be careful, the following command would remove all files in the
current directory:

rm *

You can remove a directory that you own with the "rmdir" command. The
directory must be empty before it can be removed. Use the "ls -a" command
to make sure you have removed any hidden files.

Remember: the rm command is used to delete files. Once deleted, a file cannot
be restored by yourself.

12. rename files (mv)

Use the command 'mv <file1> <file2>' to rename <file1> as <file2>.

This command can also be used to move a file or a directory to another directory.

13. copy file (cp)

Use the command 'cp <file1> <file2>' to copy the contents of <file1> into <file2>.

14. examining files (more, cat)

• Use the command 'more <file>' to examine the contents of the file <file>.

• Use the command 'cat <file>' to examine the contents of an entire file at once

• More commonly, cat is used for concatenating several files into one.

cat mon tue wed thur fri > week

Note the '>' sign. It is used to indicate that the output (stdout) will go into the file 'week'.

14. make directory (mkdir)

Use the command 'mkdir <name>' to make a new directory <name>.

15. remove directory (rmdir)

Use the command 'rmdir <name>' to remove the directory <name>.

16. compiling a C++ program (g++)

a. compilation errors

If the compiler finds any errors, they will be listed by line number of your program.
You should fix all the errors in your program. One misplaced ; or missing } or */ can set off several error messages.

b. producing executables

• Use the command 'g++ <file>.cpp' to compile c++ program file <file>.cpp and produce the default executable file 'a.out'

• Use the command 'g++ -g -o <file> <file>.cpp' to compile c++ program file <file>.cpp' and produce the executable file named <file> instead of 'a.out'.

• If you want want to create and compile the individual modules of your system separately, you need do that as followings:

g++ -g -c <file>.cpp

--create the executable as follows:

g++ -g -o <file> *.o

c. running executable

Just type the name of the executable.

17. putting jobs in the background

Perform commands in the background by ending the command with a '&'.
Issuing commands in such a manner is particularly useful for long running
jobs or ones that provide their own user interface window.

18. using a source level debugger (ddd and gdb)

ddd is a graphical user interface (GUI) to many source-level debuggers. By default on linprog, it's the GUI for the gdb debugger. It provides visual feedback and mouse input for the user to control program execution through breakpoints, to examine and traverse the function call stack, to display values of variables and data structure and to browse source files and functions.

It is an efficient way to find out where logical errors are in a C/C++ program. Compilation errors are not considered as bugs here and they should be detected and removed with the
aid of the compiler and an editor.

Use the command 'ddd <executable> &' to invoke the debugger on your program. A window of ddd will pop up. There are several commands that you can issue. Many of the
commands on the (gdb) command line can also be issued using the mouse by selecting
a portion of the source code (e.g. a variable) and clicking on an icon near the top of the
window.

a. examine values of variables

1. print -- Print the value of a selected expression.
2. display -- Display the value of a selected expression in the display window, and
updates its value every time when execution stops.

b. cont -- Continue execution from where it stopped.

c. step -- Execute one source line, stepping into a function if the source line ontains a function call.

d. next -- Execute one source line, without stepping into any function call.

e. breakpoints -- Stop program execution at the line or in the function selected. To set a breakpoint in the program place the caret at the start of the source line or on the function name and click the break botton A stop sign will appear next to the source line.

f. delete -- Remove the breakpoint on the source line selected or the breakpoint number selected.

g. show breakpoints -- Show the current breakpoints (both active and inactive).

h. tracebacks (segmentation faults) stack -- Print a backtrace of the entire stack