One of the best thing of Vi is, it’s always installed as default in any Linux Operating System Distribution. So you will never miss it. If you are Java or PHP developer, I am sure you will miss Eclipse, but when you developing it online, Vim is the fastest. You can the automatic function completion too, as well as the list of functions. Hehe, so do not think that Vim is totally shit.

The features I used the most (I might update this post to list all the features I ever used, because it’s too many and I always forget everything, lol) :

• Automatic Word Completion
• Splitting windows Horizontally or Vertically (This is the best thing I like)
• Automatic Function Completion + its definition and arguments description (This is the second best I like)
• Buffers management about all opened files
• Jump to the file and the code which as the function() using the combination of ctags (ctags is at tool to mapping all of your codes functions and classes)
• Have a lot of shortcut to do a lot of stuff almost everything which this the main reason that make you faster editing files rather than using menus and mouse (I even cannot remember it all the shortcut, it’s the way too many out there…)

In the next post, I will surely talk about all of the useful command and shortcut

1. jobs
2. bg
3. fg
4. nice
5. renice
6. at
7. top

Anything missing, please add more

1. jobs
Command Description
Lists the jobs that you are running in the background and in the foreground.

Syntax
jobs [-p | -l] [-n] [-p] [-x] [job id]
If the prompt is returned with nothing and no information printed, that means no jobs are present

Useful options
jobs -p : list only the PID of process group leader
jobs -l : list only jobs that have change status since last notified by their status
jobs -r : resrict output to running jobs
jobs -s : restrict output to stopped jobs

2. bg
Command Description
place a job in a background.  Normally user can run a job in a background, by adding ampersand (&) at the end of the command, example “sleep 10 &”.  bg is a shell command and it’s used to move a job from foreground to the background, as if it had been started with ampersand (&).  If JOB is not present, the shell’s notion of the current job is used.

Examples
a. Type “sleep 100″ –> Start a dummy job in foreground. (sleep = waits an “x” amount of second).  Press Ctrl+z to stop the current job.
b. Type “bg” –> Move the last stopped job to background
c. Type “sleep 150″ –> Dummy job 1.  Press Ctrl+z to stop the current job
d. Type “sleep 140″ –> Dummy job 2.  Press Ctrl+z to stop the current job
e. Type “sleep 130″ –> Dummy job 3.  Press Ctrl+z to stop the current job
f. Type “jobs” –> List all active jobs.
g. Type “bg 2″ –> Move the second active job to background

3. fg
Command Description
Continues a stopped job by running it in the foreground

Example
If you are opening a file using vi, you can try Ctrl+z to let it run in the background, it will quit the vi and back to shell.  Then try type “jobs”, from there you can see what is the processes running in the background, which is those programs that you press Ctrl+z.

Follow all the steps below in order:
a. vi newfile
b. Press “Ctrl+z”
c. vi newfile2
d. Press “Ctrl+z”
e. type “jobs”
f. fg 2 –> You are opening the “vi newfile2″.  You can determine the job id by running bg command.
g. Press “Ctrl+z”
h. fg –> You are opening back to the “vi newfile” because it’s the first job were it was left off.

4. nice
Command Description
Run a command with modified priority.  It is used to run the given command with its scheduling priority adjusted.  Priority range goes from -20 (highest priority) to 19 (lowest priority)

Examples:
a. $ nice –> Prints the current priority value
b. $ nice ls –> Increment the priority value of the ls command by 10 (Default value) and run.
c. $ nice -n 5 ls –> Increment the priority value of the ls command by 5 and run.
d. # nice -n -2 ls –> Decrement the priority value of the ls command by -2 and run. (Only root can decrement, note that the shell is “#” which usually is a superuser or root)

Note that incrementing the priority value will reduce the priority level and vice versa.  Priority range is -20(high) to 19 (low).

5. renice
Command Description
renice is used to alters the scheduling priority of one or more running processes, priority ranges goes from -20 (highest priority) to 19 (lowest priority).

Examples
a. $ renice +1 123 –> Increment the priority value of a process, which has process ID number 123.
b. # renice -1 123 –> Decrement the priority value of a process, which has process ID number 123.  (Only root user can decrement).
c. $ renice +1 -p 123 -p 456 –> Increment the priority value of a process 123 and process ID 456.
d. $ renice +1 -u admin –> Increment the priority value of all processes which is owned by a user called “admin”.
e. $ renice +1 -g student –> Increment the priority value of all processes, which is owned by a group called “student”

Note that incrementing the priority value will reduce the priority level and vice versa.  Priority range is -20 (highest) to 19 (lowest).

6. at
Command Description
Schedules a command to be ran at a particular time, such as a print job late at night.

Syntax
at –> Executes commands at a specified time
atq –> Lists the user’s pending jobs, unless the user is the superuser.  In that case, everbody’s jobs are listed.  The format of the output lines (one for each job); job number, date, hour, job class.
atrm –> Deletes jobs, identified by their job number.
batch –> Executes commands when system load levels permit. In another words, when the load average drops below 1.5, or the value specified in the invocation of atrun.

Examples
a. $ at -m 01:35 < atjob –> Run the commands listed in the ‘atjob’ file at 1:35AM, in addition all output that is generated from job mail to the user running the task. When this command has been successfully enter you should receive a prompt similar to the below example.
commands will be executed using /bin/sh
job 1072250520.a at Sun May 24 00:22:00 2009
b. $ at -l –> This command will list each of the scheduled jobs as seen below.
1072250520.a Sun May 24 00:22:00 2009
c. $ at -r 1072250520.a\ –> Deletes the job just created.
or
d. $ atrm 23 = Deletes job 23.

If you wish to create a job that is repeated you could modify the file that executes the commands with another command that recreates the job or better yet use the crontab command.  Note that Performing just the at command at the prompt will give you an error “Garbled Time”, this is a standard error message if no switch or time setting is given.

7. top
Command Description
Provide information (frequently refreshed, or you can type Enter or Space to refresh it) about the most CPU-intensive, Memory or anything about processes currently running
Description of the fields
a: PID — Process Id
The task’s unique process ID, which periodically wraps, though never restarting at zero.
b: PPID — Parent Process Pid
The process ID of a task’s parent.
c: RUSER — Real User Name
The real user name of the task’s owner.
d: UID — User Id
The effective user ID of the task’s owner.
e: USER — User Name
The effective user name of the task’s owner.
f: GROUP — Group Name
The effective group name of the task’s owner.
g: TTY — Controlling Tty
The name of the controlling terminal. This is usually the device (serial port, pty, etc.) from which the process was started, and which it uses for input or output. However, a task need not be associated with a terminal, in which case you’ll see ‘?’ displayed.
h: PR — Priority
The priority of the task.
i: NI — Nice value
The nice value of the task. A negative nice value means higher priority, whereas a positive nice value means lower priority. Zero in this field simply means priority will not be adjusted in determining a task’s dispatchability./dd>
j: P — Last used CPU (SMP)
A number representing the last used processor. In a true SMP environment this will likely change frequently since the kernel intentionally uses weak affinity. Also, the very act of running top may break this weak affinity and cause more processes to change CPUs more often (because of the extra demand for cpu time).
k: %CPU — CPU usage
The task’s share of the elapsed CPU time since the last screen update, expressed as a percentage of total CPU time. In a true SMP environment, if ‘Irix mode’ is Off, top will operate in ‘Solaris mode’ where a task’s cpu usage will be divided by the total number of CPUs. You toggle ‘Irix/Solaris’ modes with the ‘I’ interactive command.
l: TIME — CPU Time
Total CPU time the task has used since it started. When ‘Cumulative mode’ is On, each process is listed with the cpu time that it and its dead children has used. You toggle ‘Cumulative mode’ with ‘S’, which is a command-line option and an interactive command. See the ‘S’ interactive command for additional information regarding this mode.
m: TIME+ — CPU Time, hundredths
The same as ‘TIME’, but reflecting more granularity through hundredths of a second.
n: %MEM — Memory usage (RES)
A task’s currently used share of available physical memory.
o: VIRT — Virtual Image (kb)
The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that have been swapped out.
VIRT = SWAP + RES.
p: SWAP — Swapped size (kb)
The swapped out portion of a task’s total virtual memory image.
q: RES — Resident size (kb)
The non-swapped physical memory a task has used.
RES = CODE + DATA.
r: CODE — Code size (kb)
The amount of physical memory devoted to executable code, also known as the ‘text resident set’ size or TRS.
s: DATA — Data+Stack size (kb)
The amount of physical memory devoted to other than executable code, also known as the ‘data resident set’ size or DRS.
t: SHR — Shared Mem size (kb)
The amount of shared memory used by a task. It simply reflects memory that could be potentially shared with other processes.
u: nFLT — Page Fault count
The number of major page faults that have occurred for a task. A page fault occurs when a process attempts to read from or write to a virtual page that is not currently present in its address space. A major page fault is when disk access is involved in making that page available.
v: nDRT — Dirty Pages count
The number of pages that have been modified since they were last written to disk. Dirty pages must be written to disk before the corresponding physical memory location can be used for some other virtual page.
w: S — Process Status
The status of the task which can be one of:
‘D’ = uninterruptible sleep
‘R’ = running
‘S’ = sleeping
‘T’ = traced or stopped
‘Z’ = zombieTasks shown as running should be more properly thought of as ‘ready to run’ — their task_struct is simply represented on the Linux run-queue. Even without a true SMP machine, you may see numerous tasks in this state depending on top’s delay interval and nice value.
x: Command — Command line or Program name
Display the command line used to start a task or the name of the associated program. You toggle between command line and name with ‘c’, which is both a command-line option and an interactive command.When you’ve chosen to display command lines, processes without a command line (like kernel threads) will be shown with only the program name in parentheses, as in this example:( mdrecoveryd )

Either form of display is subject to potential truncation if it’s too long to fit in this field’s current width. That width depends upon other fields selected, their order and the current screen width. Note that The ‘Command’ field/column is unique, in that it is not fixed-width. When displayed, this column will be allocated all remaining screen width (up to the maximum 512 characters) to provide for the potential growth of program names into command lines.

y: WCHAN — Sleeping in Function
Depending on the availability of the kernel link map (’System.map’), this field will show the name or the address of the kernel function in which the task is currently sleeping. Running tasks will display a dash (’-’) in this column.Note: By displaying this field, top’s own working set will be
increased by over 700Kb. Your only means of reducing that overhead
will be to stop and restart top.
z: Flags — Task Flags
This column represents the task’s current scheduling flags which are expressed in hexadecimal notation and with zeros suppressed. These flags are officially documented in . Less formal documentation can also be found on the ‘Fields select’ and ‘Order fields’ screens.

Interactive commands
While top is running you may issue some options that will interact immediately with top these options are:
h –> Help, displays a summary of command that will modify the behavior of top
k –> Kills a process, you will be able to kill only your own processes, unless you are running top as root
n –> Once this command is entered top will ask you how many lines you want on your screen, if you enter 0 top will display as much as it can
q –> Exits top
r –> Change the priority of a process, as well as with k you will only be able to act on your own processes unless you are root
W –> Writes the current configuration to your personal configuration file, which is $HOME/.toprc
> –> Re-order the processes to the right column
< –> Re-order the processes to the left column

Next is you should now 7 administration useful Linux commands, like “jobs”

Last time I talked about speeding up your Linux by tweaking your boot loader GRUB, BIOS, running services and servers or daemons and etc. Now it’s about Filesystem…

1. Start a terminal.
2. Switch to root using the “su -” command.
3. Backup your fstab using the command: “cp /etc/fstab /etc/fstab.old”
4. Open your /etc/fstab in the editor of your choice (nano, kate or gedit recommended, but I prefer vim, it’s the BEST recommendation from me!!). This can be done by issuing the command “nano /etc/fstab”, “kate /etc/fstab”, or “gedit /etc/fstab”, but do not forget also “vim /etc/fstab”
5. Locate the partitions that contain your / and /home file systems, as well as any other file system you want to optimize. Examples include /dev/hda2 and /dev/hda3, or /dev/sda2 and /dev/sda3.
6. In the fourth section (just before the two numbers at the end of the line) you will see the options section of the fstab, e.g. “iocharset=utf8,nosuid” and etc..
7. Enter “,noatime,nodiratime” after the existing options for each partition you wish to optimize.
   Save the fstab file.
8. Reboot.

Enjoy your newly optimized Linux ext3 file system. And if you don’t believe it is 40% check out the website kerneltrap.org.

P.S.: Please notice that If you are using programs such as tmpwatch, mutt, or mail-notify this configuration change could cause those programs that make specific use of atime not to work.

• If you do not use any USB devices add “no usb” in the GRUB menu
• If you are running a server and don’t need a GUI add “3″. After that you can install Webmin to manage from a web browser
• Rather than webmin, I prefer using ssh Just need to install ssh server, and you can access it remotely

Some BIOS hacks are important to speed up the boot process. Enter your BIOS and do the following:

• Disable booting from CD-ROM and floppy (if you still have one). You can always use the hotkey like “del” or “F12″ or “Esc” depends on your motherboard to access the boot menu when you turn the PC on
• Look for a setting called Quick Boot, or Quick Power On Self Test. Enable this if you have this option.

Inside the Linux system. Disable unneeded services. This depends on a lot of things. Are you running a server? Are you running a laptop? Look through your services with the chkconfig –list command to see what is enabled. Note that different distributions might not using this, this chkconfig command is a common way any Red Hat based Distributions. See here on how to use chkconfig to disable services. Here are some suggestions:

• If you don’t print disable CUPS
• Bluetooth, you know if you need it
• If you don’t know what NFS stands for, disable it.
• SSH, do you SSH into your box? If not disable it. (Hey I used it always for the server, but what it needs for on a laptop?) You know when you want it.
• iptables, it’s a common Linux Firewall. Most broadband modems or routers have firewalls built in. Disable it unless you didn’t secure your wireless. But I don’t know if you need double firewall, one in the router, one in your system
• I remember I have to do “sudo apt-get remove tracker” in Ubuntu 7.10 because it always slowing my machine at around 5:00 PM !!  Even now in Jaunty 9.04 Ubuntu!!
• In ubuntu, you can go to System -> Preferences –> Sessions.  Disable shitty services there
• Check using top command or htop command to see what programs and services make you slow
• Well, you know the idea, remove useless softwares, useless server stuff like NFS, SSHD, CUPS, etc !!

Did you know that on most distributions you can use the Alt+F1 to F7 to switch to virtual consoles? You can disable this by editing /etc/inittab. Be careful editing this file back it up if you are unsure. Look for lines like this:
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
4:2345:respawn:/sbin/mingetty tty4
5:2345:respawn:/sbin/mingetty tty5
6:2345:respawn:/sbin/mingetty tty6

Erase them all!! Hehe, JUST JOKING, lol. Comment 3-6 with a # sign at the beginning of each line. For example

#3:2345:respawn:/sbin/mingetty tty3
#4:2345:respawn:/sbin/mingetty tty4
#5:2345:respawn:/sbin/mingetty tty5
#6:2345:respawn:/sbin/mingetty tty6

Again, on another distribution it might be not in /etc/inittab

Recompile your kernel it’s the best way to tweak up your system. This is a whole other topic, that I have to talk about it next time !!