octave:1> A = [ 1, 1, 2; 3, 5, 8; 13, 21, 34 ] (Create matrix to store for later. printout)
octave:2> B = rand (3, 2); (Create matrix 3 rows 2 columns, random vars, no printout)
octave:3> B (Display B)
octave:4> 2 * A (Matrix A times scalar a)
octave:5> A * B (Matrix matrix multiply)
octave:6> A' * A (transpose (A) * A)
octave:7> A \ b (solveAx= b)
| Command | Function |
| ls | Short listing of directory contents |
| cd [dirname] | Change directory to [dirname] |
| cd .. | Change directory and go back a level |
| cd | Change back to your home directory |
cd  | Change back to your home directory |
| cp [oldfile] [newfile] | Copy a file |
| mv [oldpath/oldfile] [newpath/newfile] | Move or rename a file |
| rm [file_to_delete] | Delete a file (files are unrecoverable) |
| gzip [file_to_compress] | Compress a file using gzip |
| gunzip [file_to_uncompress] | Uncompress a gzipped file |
| mkdir [new_dir_name] | Create a directory in the current directory |
| rmdir [dir_to_delete] | Remove a directory (if it is empty) |
| man [command] | Get the manual pages for [command] |
Hints:
System configuration
shell bash;
different accounts ;
User needs to have personal groups (user radio belongs to group students, ..);
su;
virtual console
1.2 Access to the system and logout
Let's start with something wrong.
login: redio[Enter]
Even if the account doesn't exist you'll be asked for a password
Password: radio2001[Enter]
Login incorrect
Let's start again
login: radio[Enter]
Password: 2001[Enter]
Last login: Sun Nov 11 10:45:11 on tty1
You get information about your last access
The prompt shell means the system is ready to receive your commands.
$
1.2.1 Switching account
logging out and then logging in with a different account
using su.
$ su root[Enter]
Password: smr1301[Enter]
If it is the right password you get identity and the rights of the typed user.
1.2.2 Virtual Consoles
[Alt+Fn] (where n is in the range 1..6).
You can start another login session on a different console
1.2.3 Who am I?
When you have more then one account may be necessary to check which account you are using.
$ whoami[Enter]
root
whoami let you know under which identity you are working on.
$ logname[Enter]
radio
logname allows you to know what account you used when you first entered in the system (login).
1.2.4 Ending a session
Just need to end the shell, that is the program that shows the prompt.
$ whoami[Enter]
root
$ exit[Enter]
In case we had used su
$ whoami[Enter]
radio
This exit closes last shell, and logs the user out of the system.
$ exit[Enter]
login:
1.2.5 Shutting down
login: root[Enter]
Password: smr1301[Enter]
# shutdown -h now[Enter]
System is going down NOW!!
...
System halted
When this happens it is possible to reboot the system.
---------
You can use su to become root and shutdown the system.
$ su[Enter]
Password: smr1301[Enter]
# shutdown -h now[Enter]
1.3 Password management
1.3.1 User root changes password to regular user
# passwd radio[Enter]
New UNIX password: 123[Enter]
The password is too short, the system advises you but it doesn't stop you from using it.
BAD PASSWORD: it's a WAY too short
Retype new UNIX password: 123[Enter]
passwd: all authentication tokens updated successfully
1.3.2 Regular user changes its password
$ passwd[Enter]
You'll be asked for the old password.
Changing password for radio
(current) UNIX password: 123[Enter]
New UNIX password: elpoep[Enter]
BAD PASSWORD: it is based on a (reversed) dictionary word
passwd: Authentication token manipulation error
$ passwd[Enter]
Changing password for radio
(current) UNIX password: 123[Enter]
New UNIX password: I cannot understand PCs[Enter]
Retype new UNIX password: I cannot understand PCs[Enter]
passwd: all authentication tokens updated successfully
1.4 Moving around directories
The filesystem is organizated in directory and subdirectory.
1.4.1 Current Directory
$ cd /usr/bin[Enter]
$ pwd[Enter]
/usr/bin
1.4.2 Absolute and relative path
The absolute path starts from the root directory while the relative one starts from the current directory.
$ cd /usr/local[Enter]
This is an absolute path since it starts with /.
$ pwd[Enter]
/usr/local
$ cd bin[Enter]
This is a relative one: it starts from the local directory moving downward to bin.
$ pwd[Enter]
/usr/local/bin
1.4.3 Moving backward
Every directory holds two references to special subdirectory:
single (.) that is a reference to the current directory.
double (..) that is a reference to the previous directory.
These symbols are effective directory names.
$ cd ..[Enter]
$ pwd[Enter]
/usr/local
$ cd ../bin[Enter]
$ pwd[Enter]
/usr/bin
You may go backward for more then one level.
$ cd ../../var/tmp[Enter]
$ pwd[Enter]
/var/tmp
$ pwd[Enter]
/usr/local
1.4.4 The precise reference to the current directory
The current directory can be seen as a single dot. In practice all relative paths can start with the prefix ./.
$ cd ./bin[Enter]
$ pwd[Enter]
/usr/local/bin
1.4.5 Home Directory
Every user has his own personal directory, known as home, it keeps all the data owned by the user. Typing just cd the user can reach his home directory.
$ cd[Enter]
$ pwd[Enter]
/home/radio
Some shells replace tilde (~) at the begging of a path with the path of the home directory of the working user.
$ cd ~[Enter]
$ pwd[Enter]
/home/radio
In the same way if tilde is set before a user account it will be replaced with the path of user's home directory.
$ cd ~ftp[Enter]
$ pwd[Enter]
/home/ftp
Going back to home directory.$ cd[Enter]
1.5 File content
1.5.1 Directory content
To list the directory content command ls is used
$ ls /bin[Enter]
arch dd gzip netconf sleep
ash df hostname netstat sort
ash.static dmesg igawk nice stty
aumix-minimal dnsdomainname ipcalc nisdomainname su
awk doexec kill ping sync
basename domainname linuxconf ps tar
bash echo ln pwd tcsh
bash2 ed loadkeys red touch
bsh egrep login remadmin true
cat ex ls rm umount
chgrp false mail rmdir uname
chmod fgrep mkdir rpm userconf
chown fsconf mknod rvi usleep
consolechars gawk mktemp rview vi
cp gawk-3.0.4 more sed view
cpio grep mount setserial vimtutor
csh gtar mt sfxload ypdomainname
date gunzip mv sh zcat
The command ls /bin lists the content of /bin/.
A more expressive listing can be obtened using option -l.
$ ls -l /bin[Enter]
-rwxr-xr-x 1 root root 2612 Mar 7 11:29 arch
-rwxr-xr-x 1 root root 60592 Feb 3 20:12 ash
-rwxr-xr-x 1 root root 263064 Feb 3 20:12 ash.static
-rwxr-xr-x 1 root root 9968 Feb 3 19:04 aumix-minimal
lrwxrwxrwx 1 root root 4 Apr 13 23:28 awk -> gawk
-rwxr-xr-x 1 root root 5756 Mar 7 12:15 basename
-rwxr-xr-x 1 root root 316848 Feb 27 18:44 bash ... many lines ...
-rwxr-xr-x 1 root root 4320 Mar 7 12:15 true
-rwsr-xr-x 1 root root 26608 Feb 3 15:14 umount
-rwxr-xr-x 1 root root 6196 Mar 7 12:15 uname
lrwxrwxrwx 1 root root 14 Apr 13 23:49 userconf -> /bin/linuxco
nf
-rwxr-xr-x 1 root root 16252 Mar 8 17:26 usleep
-rwxr-xr-x 1 root root 346352 Mar 7 18:18 vi
lrwxrwxrwx 1 root root 2 Apr 14 00:00 view -> vi
-rwxr-xr-x 1 root root 362 Mar 7 18:18 vimtutor
lrwxrwxrwx 1 root root 8 Apr 13 23:51 ypdomainname -> hostname
-rwxr-xr-x 3 root root 46384 Feb 15 17:04 zcat $ cd[Enter]
$ ls[Enter]
To list hidden files
$ ls -a[Enter]
. .bash_history .enlightenment .mc
.. .bash_logout .gnome .tcshrc
.ICEauthority .bash_profile .gnome-desktop .xsession-errors
.Xauthority .bashrc .gnome-help-browser
.Xdefaults .cshrc .gnome_private 1.5.2 File Content
In order to analyse the file content cat,less and more ca be used (it doesn't make sense if it is a binary file).
$ cat /etc/issue[Enter]
Red Hat Linux release 6.2 (Zoot)
Kernel 2.2.14-5.0 on an i586
1.5.3 Find out the file type
file is command the uses the so called magic number (Unix tradition) to figure out the file type..
$ file /etc/*[Enter]
/etc/CORBA: directory
/etc/DIR_COLORS: English text
/etc/HOSTNAME: ASCII text
/etc/X11: directory
/etc/adjtime: ASCII text
/etc/aliases: English text
...many lines...
/etc/shells: ASCII text
/etc/skel: directory
/etc/smb.conf: English text
/etc/smrsh: directory
/etc/snmp: directory
/etc/sound: directory
/etc/sysconfig: directory
/etc/sysctl.conf: English text
/etc/syslog.conf: English text
/etc/termcap: English text
/etc/up2date.conf: can't read `/etc/up2date.conf' (Permission denied).
/etc/vga: directory
/etc/yp.conf: English text
/etc/ypserv.conf: English text
This method is not realible but can be useful.
1.5.4 Used and free space
In order to check the free space on disk you can use df.
$ df[Enter]
The result maybe something similar to this one.
Filesystem 1k-blocks Used Available Use% Mounted on
/dev/hda5 1511968 805300 629860 56% /
/dev/hda1 99521 2482 91900 3% /boot
To check the directory used space: du.
$ du /bin[Enter]
5240 /bin
In this case the /bin/ directory holds files for a total amount of 5240KB.
1.6 File creation, copy and deletion
1.6.1 File creation
There are different ways to create a file. The easiest way to create an empty file si to use touch. First move to the home directory, the best place where to play.
$ cd[Enter]
$ touch myfile[Enter]
$ ls -l myfile[Enter]
-rw-rw-r-- 1 radio radio 0 Dec 23 10:49 myfile
The file was created..
You can use cat too:
$ cat > myfile2[Enter]
there are better ways to write[Enter]
text.[Enter]
This is a oneway writing.[Enter]
[Ctrl+d]
$ cat myfile2[Enter]
1.6.2 File copy
$ cp myfile2 myfile3[Enter]
Group copy is possible only if the last file is an existing directory.
$ cp myfile myfile2 myfile3 /tmp[Enter]
$ cp myfile* /tmp[Enter]
1.6.3 File deletion
Becareful when you delete something as root!!
$ rm myfile myfile2[Enter]
There is noway to recover deleted files.
You can use the wild chars:* and ?.
$ ls myfile*[Enter]
myfile3
$ rm myfile*[Enter]
1.7 Working with directory
1.7.1 Directory creation
$ cd[Enter]
$ mkdir mydir[Enter]
Let's check with ls.
$ ls -l[Enter]
...
drwxr-xr-x 8 radio radio 1024 Dec 23 12:11 mydir
...
The d character at the beginning of the string tells has that the file is a directory.
1.7.2 Directory copy
cp with option -r or-R.
$ cp -r mydir mydir2[Enter]
1.7.3 Directory deletion
You may delete an empty directory using rmdir.
$ rmdir mydir2[Enter]
Let's try with something more complex.
$ mkdir carbon[Enter]
$ mkdir carbon/hydrogen[Enter]
$ mkdir carbon/oxygen[Enter]
$ mkdir carbon/hydrogen/helium[Enter]
$ rmdir carbon[Enter]
rmdir: carbon: Directory not empty
$ rm -r carbon[Enter]
1.8 Moving around directories and linking files
In Unix environment rename and moving a file are the same thing.
1.8.1 Moving and renaming
The command used is mv.
$ touch white[Enter]
$ touch green[Enter]
$ mkdir purple[Enter]
Let's check.
$ ls -l[Enter]
...
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 white
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 green
drwxrwxr-x 2 radio radio 1024 Dec 25 12:46 purple
...
Let's rename white file to make it brown.
$ mv white brown[Enter]
$ ls -l[Enter]
...
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 brown
...
To move more file all in once the destination must be a directory.
$ mv brown green purple[Enter]
$ ls -l purple[Enter]
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 green
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 brown
$ mv purple /tmp[Enter]
1.8.2 Linking
Instead of copying a file we may want to create a reference to it. There are two kind of links that can be created hard links and soft links. Let's see the soft one
The command is ln with the option -s.
Let's set the environment.
$ touch one[Enter]
$ touch two[Enter]
$ mkdir three[Enter]
Checking ..
$ ls -l[Enter]
...
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 two
drwxrwxr-x 2 radio radio 1024 Dec 25 12:46 three
-rw-rw-r-- 1 radio radio 0 Dec 25 12:46 one
$ ln -s one one.bis[Enter]
$ ls -l[Enter]
...
lrwxrwxrwx 1 radio radio 3 Dec 25 12:47 one.bis -> one
It's the same for directories.
$ ln -s /tmp miatemp[Enter]
$ ln -s /home/radio/one* /home/radio/two three[Enter]
$ ls -l three[Enter]
lrwxrwxrwx 1 radio radio 15 Dec 25 15:21 two -> /home/radio/two
lrwxrwxrwx 1 radio radio 15 Dec 25 15:21 one -> /home/radio/one
lrwxrwxrwx 1 radio radio 19 Dec 25 15:21 one.bis -> /home/radio/one.bis
1.9 The shell
The shell is the way to interact with the operative systme. The shell bash is the one used in our exercises.
1.9.1 Automatic fulfilling
The shell can fulfill a command using [Tab], this feature is particularly useful when you have file with long names.
$ touch microprocessor[Enter]
$ touch microscopic[Enter]
$ touch supersonic[Enter]
$ ls sup[Tab]
$ ls sup[Tab]ersonic[Enter]
$ ls mic[Tab]ro
$ ls mic[Tab]rop[Tab]rocessor[Enter]
1.9.2 Substitution: wild char
This is an alternative way to fulfill a command, it is the the shell that changes symbols with the right information.
1.9.2.1 Asterisk *
That symbol can be replaced with a sequence, from 0 to infinity, of symbols.
$ ls[Enter]
$ ls *[Enter]
This command is different, the shell changes the * with the list of files and directory held in the current directory. This means that if there is any subdirectory its content
would be displayed.
ls micro*[Enter]
microprocessor microscopic
* can be changed with null string:
$ touch millimicro[Enter]
$ ls *micro*[Enter]
microprocessor microscopic millimicro
The question mark ? can be change with just one symbol
Let's create some files.
$ touch xy123j4[Enter]
$ touch xy456j5[Enter]
$ touch xy789j111[Enter]
$ touch xy78j67[Enter]
$ ls [Enter]
xy123j4
xy456j5
xy789j111
xy78j67
$ ls ?????j?[Enter]
xy123j4
xy456j5
$ ls *j*[Enter]
xy123j4 xy456j5 xy789j111 xy78j67
1.9.2.3 Square brackets [ ]
The square brackets are used to have a range of symbols from which to choose the substitution symbols. Just one symbol from the one listed is used.
$ ls xy????[4567]*[Enter]
xy123j4 xy456j5$ ls xy????[4-7]*[Enter]
1.9.2.4 Escape
For some special symbols you need to use escape
$ touch six\*height[Enter]
$ ls[Enter]
...
six*height
If you create a filename with a space inside
$ touch my\ letter[Enter]
$ ls[Enter]
...
my letter
six*height
1.9.3 Input/Output redirection and pipeline
The shell allows you to redirect command output from the standard output (usually the screen). The same for the input.
1.9.4 Redirection
$ ls -l > mylist[Enter]
$ cat mylist[Enter]
For the input .. instead of using the standard input (keyboard).
$ cat < mylist[Enter]
Appending to a file.
$ ls -l /tmp >> mylist[Enter]
$ cat mylist[Enter]
1.9.5 Pipeline
The pipeline is a way of redirecting input and output commands.
$ cat mylist | sort[Enter]
$ cat <>
Make it easier but without using pipeline.
$ sort <>
1.9.6 Alias
Aliases allows you to create an alternative name to an existing command.
$ alias ll='ls -l'[Enter]
$ ll[Enter]
This alias take options as an ordinary command.
$ ll micro*[Enter]
It's the same as ls -l micro*.
-rw-rw-r-- 1 radio radio 0 Dec 26 10:19 microprocessor
-rw-rw-r-- 1 radio radio 0 Dec 26 10:19 microscopic
This are the aliases that are usually created to avoid mistake
$ alias rm='rm -i'[Enter]
$ alias cp='cp -i'[Enter]
$ alias mv='mv -i'[Enter]
Now try to remove a file.
$ rm microprocessor[Enter]
rm: remove `microprocessor'?:
n[Enter]
In this way the file was not removed.
1.10 Searching
Searching files or directories it's an important task in a filesystem as complex as the Linux (or Unix) one.
1.10.1 Find
Searching a file or directory using its name or other external feature find command is used.
$ find / -name bash -print[Enter]
This command search for files and directory named bash inside all the directory starting from the root directory (/).
/bin/bash
...
find: /var/run/sudo: Permission denied
find: /var/spool/at: Permission denied
find: /var/spool/cron: Permission denied
...
You can use wild chars, in this case it will be the find command that will have to manage them, without using shell.$ find / -name \*sh -print[Enter]
The escape char \ tells the shell not to translate the * as wild char.
/bin/bash
/bin/ash
/bin/sh
...
1.10.2 Grep
To search inside the content of a file grep is used.
$ grep radio /etc/*[Enter]
/etc/group:radio::500:radio
/etc/passwd:radio:Ide2ncPYY1234:500:500:radiolab:/home/radio:/bin/bash
grep: /etc/skel: Is a directory
grep: /etc/sudoers: Permission denied
...
1.16 References
Matt Chapman, Frankie Blaskovic, The Guide -- A Beginners Guide to UNIX
http://www.belgarath.demon.co.uk/guide/
Christopher C. Taylor, Unix is a Four Letter Word... and Vi is a Two Letter Abbreviation
http://www.linuxbox.com/~taylor/4ltrwrd/
You can also execute multiple commands by separating each one with a ; for example cd newdir; mkdir thatdir ; ls -la will first change directories to the newdir directory, then create a directory called thatdir, then list all the files in long format. You can string together as many commands as you like but caution should be used not to inadvertently do anything harmful.
If you think some thing need to be added to this list let me know.
access - determine whether a file can be accessed
Syntax
access -mode file
For more options and how to use check access man page
alias - define or display aliases
Syntax
alias [alias-name[=string] …]
For more options and how to use check alias man page
bg - run jobs in the background
Syntax
bg [job_id …]
For more options and how to use check bg man page
cal - displays a calendar
Syntax
cal [-smjy13 ] [[ month ] year ]
For more options and how to use check cal man page
cd - change directories
Use cd to change directories. Type cd followed by the name of a directory to access that directory.Keep in mind that you are always in a directory and can navigate to directories hierarchically above or below.
Syntax
cd [-L | -P] [directory]
For more options and how to use check cd man page
chown - change file owner and group
Syntax
chown [OPTION] OWNER[:[GROUP]] FILE
chown [OPTION] :GROUP FILE
chown [OPTION] –reference=RFILE FILE
For more options and how to use check chown man page
chmod - change file access permissions
Syntax
chmod [-r] permissions filenames
Options
r Change the permission on files that are in the subdirectories of the directory that you are currently in. permission Specifies the rights that are being granted. Below is the different rights that you can grant in an alpha numeric format.filenames File or directory that you are associating the rights with Permissions
u - User who owns the file.
g - Group that owns the file.
o - Other.
a - All.
r - Read the file.
w - Write or edit the file.
x - Execute or run the file as a program.
Numeric Permissions:
CHMOD can also to attributed by using Numeric Permissions:
400 read by owner
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody
For more options and how to use check chmod man page
cp - Copy files and directories
Syntax
cp [OPTION]… SOURCE DEST
cp [OPTION]… SOURCE… DIRECTORY
cp [OPTION]… –target-directory=DIRECTORY SOURCE…
Options
cp myfile yourfile
Copy the files “myfile” to the file “yourfile” in the current working directory. This command will create the file “yourfile” if it doesn’t exist. It will normally overwrite it without warning if it exists.
cp -i myfile yourfile
With the “-i” option, if the file “yourfile” exists, you will be prompted before it is overwritten.
cp -i /data/myfile
Copy the file “/data/myfile” to the current working directory and name it “myfile”. Prompt before overwriting the file.
cp -dpr srcdir destdir
Copy all files from the directory “srcdir” to the directory “destdir” preserving links (-poption), file attributes (-p option), and copy recursively (-r option). With these options, a directory and all it contents can be copied to another dir
For more options and how to use check cp man page
clear - Clears the terminal screen.
Syntax
clear
For more options and how to use check clear man page
cmp - Compares two files, reporting all discrepancies. Similar to the diff command, though the output format differs.
Syntax
cmp [-clsv] [-i NUM] [–help] [–print-chars] [–ignore-initial=NUM] [–verbose] [–quiet] [–silent] [–version] -I FILE1 [FILE2 [RANGE1 [RANGE2]]]
For more options and how to use check cmp man page
cat - Sends file contents to standard output. This is a way to list the contents of short files to the screen. It works well with piping.
Syntax
cat [OPTION] [FILE]…
For more options and how to use check cat man page
diff - find differences between two files
Syntax
diff [options] from-file to-file
For more options and how to use check diff man page
dmesg - Prints the messages resulting from the most recent system boot.
Syntax
dmesg [ -c ] [ -n level ] [ -s bufsize ]
For more options and how to use check dmesg man page
du - estimate file space usage
Syntax
du [OPTION]… [FILE]…
For more options and how to use check du man page
df - report filesystem disk space usage
Syntax
df [OPTION]… [FILE]…
For more options and how to use check df man page
exit - cause the shell to exit
syntax
exit [n]
For more options and how to use check exit man page
eject - eject removable media
Syntax
eject -h
eject [-vnrsfqp] []
eject [-vn] -d
eject [-vn] -a on|off|1|0 []
eject [-vn] -c slot []
eject [-vn] -t []
eject [-vn] -x []
eject -V
For more options and how to use check eject man page
fuser - identify processes using files or sockets
Syntax
fuser [-a|-s|-c] [-4|-6] [-n space] [-k [-i] [-signal] ] [-muvf] name
fuser -l
fuser -V
For more options and how to use check fuser man page
fsck - check and repair a Linux file system
Syntax
fsck [ -sACVRTNP ] [ -t fstype ] filesys [ … ] [–] [ fsck-options ]
For more options and how to use check fsck man page
fdisk - Partition table manipulator for Linux
Syntax
fdisk [-u] [-b sectorsize] [-C cyls] [-H heads] [-S sects] device
fdisk -l [-u] device …
fdisk -s partition …
fdisk -v
For more options and how to use check fdisk man page
fg - run jobs in the foreground
Syntax
fg [job_id]
For more options and how to use check fg man page
file - determine file type
Syntax
file [ -bciknsvzL ] [ -f namefile ] [ -m magicfiles ] file …
file -C [ -m magicfile ]
For more options and how to use check file man page
find - search for files in a directory hierarchy
Syntax
find [path…] [expression]
For more options and how to use check find man page
finger - Prints descriptions of the specified users.
Syntax
finger [-lmsp ] [user … ] [user@host … ]
For more options and how to use check finger man page
free - Displays the amount of used and free system memory.
Syntax
free [-b | -k | -m] [-o] [-s delay ] [-t] [-V]
For more options and how to use check free man page
ftp - A File Transfer Protocol client
Syntax
ftp hostname or ipaddress
For more options and how to use check ftp man page
grep, egrep, fgrep - print lines matching a pattern
Syntax
grep [options] PATTERN [FILE…]
grep [options] [-e PATTERN | -f FILE] [FILE…]
For more options and how to use check grep, egrep, fgrep man page
head - output the first part of files
Syntax
head [OPTION]… [FILE]…
For more options and how to use check head man page
history - Manipulate the history list
Syntax
history option arg arg …
For more options and how to use check history man page
!!
use the ! option. To automatically re-display the last command you typed at the prompt, type: !! and press enter. Press again to invoke the command. You can also automatically re-display a command you typed earlier by using the ! and the first few letters of the command.
& operator
execute a command as a background process.
Ex:-
#top&
init - process control initialization
Syntax
/sbin/init [ -a ] [ -s ] [ -b ] [ -z xxx ] [ 0123456Ss ]
For more options and how to use check init man page
ispell - ispell, buildhash, munchlist, findaffix, tryaffix, icombine, ijoin - Interactive spelling checking
Syntax
ispell [common-flags] [-M|-N] [-Lcontext] [-V] files
ispell [common-flags] -l
ispell [common-flags] [-f file] [-s] {-a|-A}
ispell [-d file] [-w chars] -c
ispell [-d file] [-w chars] -e[e]
ispell [-d file] -D
ispell -v[v]
For more options and how to use check ispell man page
id - Print real and effective user id (uid) and group id (gid), prints options about the given user, or if no user is specified the process running it
Syntax
id [options]… [username]
For more options and how to use check id man page
kill - terminate a process
Syntax
kill [ -s signal | -p ] [ -a ] [ — ] pid … kill -l [ signal ]
For more options and how to use check kill man page
killall - kill processes by name
Syntax
killall [-Z,–context pattern] [-e,–exact] [-g,–process-group] [-i,–interactive] [-q,–quiet] [-r,–regexp] [-s,–signal signal] [-u,–user user] [-v,–verbose] [-w,–wait] [-I,–ignore-case] [-V,–version] [–] name … killall -l killall -V,–version
For more options and how to use check killall man page
logname - Print current login name
Syntax
logname [OPTION]
For more options and how to use check logname man page
less - Opposite of the more command
Syntax
less -?
less –help
less -V
less –version
less [-[+]aBcCdeEfFgGiIJmMnNqQrRsSuUVwWX]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,…] [-y lines] [-[z] lines]
[+[+]cmd] [–] [filename]…
For more options and how to use check less man page
logout - to quit using the system
Syntax
logout
lsof - list open files
Syntax
lsof [ -?abChlnNOPRstUvVX ] [ -A A ] [ -c c ] [ +c c ] [ +|-d d ] [ +|-D D ] [ +|-f [cfgGn] ] [ -F [f] ] [ -g [s] ] [ -i [i] ] [ -k k ] [ +|-L [l] ] [ +|-m m ] [ +|-M ] [ -o [o] ] [ -p s ] [ +|-r [t] ] [ -S [t] ] [ -T [t] ] [ -u s ] [ +|-w ] [ -x [fl] ] [ -z [z] ] [ — ] [names]
For more options and how to use check lsof man page
ls - Short listing of directory contents
Syntax
ls [OPTION]… [FILE]…
Options
-a list hidden files
-d list the name of the current directory
-F show directories with a trailing ‘/’
executable files with a trailing ‘*’
-g show group ownership of file in long listing
-i print the inode number of each file
-l long listing giving details about files and directories
-R list all subdirectories encountered
-t sort by time modified instead of name
For more options and how to use check ls man page
ln - make links between files
Syntax
ln [OPTION]… TARGET [LINK_NAME]
ln [OPTION]… TARGET… DIRECTORY
ln [OPTION]… –target-directory=DIRECTORY TARGET…
Option
ln -s test symlink
Creates a symbolic link named symlink that points to the file test Typing “ls -i test symlink” will show the two files are different with different inodes. Typing “ls -l test symlink” will show that symlink points to the file test.
For more options and how to use check ln man page
locate - list files in databases that match a pattern
Syntax
locate [-d path | –database=path] [-e | –existing] [-i | –ignore-case ] [–version] [–help] pattern…
For more options and how to use check locate man page
mail - Launches a simple mail client that permits sending and receiving email messages.
Syntax
mail [OPTION…] [address…]
For more options and how to use check mail man page
man - an interface to the on-line reference manuals
Syntax
man [-c|-w|-tZHT device] [-adhu7V] [-m system[,…]] [-L locale] [-p string] [-M path] [-P pager] [-r prompt] [-S list] [-e extension] [[section] page …] …
man -l [-7] [-tZHT device] [-p string] [-P pager] [-r prompt] file …
man -k [apropos options] regexp …
man -f [whatis options] page …
For more options and how to use check man man page
mkdir - make directories
Syntax
mkdir [OPTION] DIRECTORY
Options
Create the Directory(ies), if they do not already exist.
Mandatory arguments to long options are mandatory for short options too.
-m, mode=MODE set permission mode (as in chmod)
-p, parents no error if existing, make parent directories as needed
-v, verbose print a message for each created directory
-help display this help and exit
-version output version options and exit
For more options and how to use check mkdir man page
mount - mount a file system
Syntax
mount [-lhV]
mount -a [-fFnrsvw] [-t vfstype] [-O optlist]
mount [-fnrsvw] [-o options [,…]] device | dir
mount [-fnrsvw] [-t vfstype] [-o options] device dir
For more options and how to use check mount man page
mv - change the name of a directory
Type mv followed by the current name of a directory and the new name of the directory
Syntax
mv [OPTION]… [-T] SOURCE DEST mv [OPTION]… SOURCE… DIRECTORY mv [OPTION]… -t DIRECTORY SOURCE…
Ex: mv testdir newnamedir
For more options and how to use check mv man page
more - Allows file contents or piped output to be sent to the screen one page at a time.
Syntax
more [-dlfpcsu ] [-num ] [+/ pattern] [+ linenum] [file … ]
For more options and how to use check more man page
nohup - run a command immune to hangups, with output to a non-tty
Syntax
nohup COMMAND [ARG]…
nohup OPTION
For more options and how to use check nohup man page
nice - run a program with modified scheduling priority
Syntax
nice [OPTION] [COMMAND [ARG]…]
For more options and how to use check nice man page
ping - send ICMP ECHO_REQUEST packets to network hosts
Syntax
ping [-Rdfnqrv ] [-c count ] [-i wait ] [-l preload ] [-p pattern ] [-s packetsize ] host
For more options and how to use check ping man page
ps - report process status
Syntax
ps [options]
For more options and how to use check ps man page
pwd - print working directory
will show you the full path to the directory you are currently in. This is very handy to use, especially when performing some of the other commands on this page.
Syntax
pwd [OPTION]
For more options and how to use check pwd man page
passwd - change user password
Syntax
passwd [-f|-s] [name]
passwd [-g] [-r|R] group
passwd [-x max] [-n min] [-w warn] [-i inact] name
passwd {-l|-u|-d|-S|-e} name
For more options and how to use check passwd man page
reboot - Reboots the system (requires root privileges).
Syntax
/sbin/halt [-n] [-w] [-d] [-f] [-i] [-p] [-h] /sbin/reboot [-n] [-w] [-d] [-f] [-i] /sbin/poweroff [-n] [-w] [-d] [-f] [-i] [-h]
For more options and how to use check reboot man page
rmdir - remove empty directories
Syntax
rmdir [OPTION]… DIRECTORY…
For more options and how to use check rmdir man page
rm - remove files or directories
Syntax
rm [OPTION]… FILE…
Option
rm -r - Removes directories and files within the directories recursively.
For more options and how to use check rm man page
renice - alter priority of running processes
Syntax
renice priority [[-p ] pid … ] [[-g ] pgrp … ] [[-u ] user … ]
For more options and how to use check renice man page
shutdown - bring the system down
Syntax
/sbin/shutdown [-t sec] [-arkhncfF] time [warning-message]
For more options and how to use check shutdown man page
sleep - delay for a specified amount of time
Syntax
sleep NUMBER[SUFFIX]…
sleep OPTION
For more options and how to use check sleep man page
sort - sort lines of text files
Syntax
sort [OPTION]… [FILE]…
For more options and how to use check sort man page
split - split a file into pieces
Syntax
split [OPTION] [INPUT [PREFIX]]
For more options and how to use check split man page
slocate - Security Enhanced version of the GNU Locate.
Syntax
slocate [-qi] [-d] [–database= ]
slocate [-i] [-r ] [–regexp=]
slocate [-qv] [-o ] [–output=] slocate [-e ] [-f ] <[-l ] [-c] <[-U ] [-u]>
slocate [-Vh] [–version] [–help]
For more options and how to use check slocate man page
sync - synchronize data on disk with memory
For more options and how to use check sync man page
su - run a shell with substitute user and group IDs
Syntax
su [OPTION]… [-] [USER [ARG]…]
For more options and how to use check su man page
telnet - user interface to the TELNET protocol
Syntax
telnet [-8] [-E] [-F] [-K] [-L] [-S tos] [-X authtype] [-a] [-c] [-d] [-e escapechar] [-f] [-k realm] [-l user] [-n tracefile] [-r] [-x] [host [port]]
For more options and how to use check telnet man page
top - display top CPU processes
Syntax
top [-] [d delay] [p pid] [q] [c] [C] [S] [s] [i] [n iter] [b]
For more options and how to use check top man page
talk - talk to another user
Syntax
talk person [ttyname]
For more options and how to use check talk man page
tree - list contents of directories in a tree-like format.
Syntax
tree [-adfgilnopqrstuxACDFNS] [-L level [-R]] [-H baseHREF] [-T title] [-o filename] [–nolinks] [-P pattern] [-I pattern] [–inodes] [–device] [–noreport] [–dirsfirst] [–version] [–help] [directory …]
For more options and how to use check tree man page
tr - translate or delete characters
Syntax
tr [OPTION]… SET1 [SET2]
For more options and how to use check tr man page
time - time a simple command or give resource usage
Syntax
time [options] command [arguments…]
For more options and how to use check time man page
tty - print the file name of the terminal connected to standard input
Syntax
tty [OPTION]…
For more options and how to use check tty man page
touch - change file timestamps
Syntax
touch [OPTION]… FILE…
For more options and how to use check touch man page
tail - output the last part of files
Syntax
tail [OPTION]… [FILE]…
For more options and how to use check tail man page
traceroute - print route packets take to network host
Syntax
traceroute [-adnruvAMOQ] [-w wait_time] [-S start_ttl] [-m max_ttl] [-p port] [-q nqueries] [-g gateway] [-t tos] [-s src_addr] [-g router] host [packet size]
For more options and how to use check traceroute man page
uptime - Tell how long the system has been running.
Syntax
uptime
uptime [-V]
For more options and how to use check uptime man page
umount - unmount file systems
Syntax
umount [-hV]
umount -a [-dflnrv] [-t vfstype] [-O options]
umount [-dflnrv] dir | device […]
For more options and how to use check umount man page
umask - get or set the file mode creation mask
Syntax
umask [-S][mask]
For more options and how to use check umask man page
ulimit - Control the resources available to a process started by the shell, on systems that allow such control.
Syntax
ulimit [-acdfHlmnpsStuv] [limit]
For more options and how to use check ulimit man page
uname - print system options
Syntax
uname [OPTION]…
For more options and how to use check uname man page
uniq - report or omit repeated lines
Syntax
uniq [OPTION]… [INPUT [OUTPUT]]
For more options and how to use check uniq man page
vdir - list directory contents
Syntax
vdir [OPTION]… [FILE]…
For more options and how to use check vdir man page
w - Show who is logged on and what they are doing.
Syntax
w - [husfV] [user]
For more options and how to use check w man page
wall - send a message to everybody’s terminal.
Syntax
wall [-n] [ message ]
For more options and how to use check wall man page
who - show who is logged on
Syntax
who [OPTION]… [ FILE | ARG1 ARG2 ]
For more options and how to use check who man page
whoami - print effective userid
Syntax
whoami [OPTION]…
For more options and how to use check whoami man page
watch - execute a program periodically, showing output fullscreen
Syntax
watch [-dhv] [-n ] [–differences[=cumulative]] [–help] [–interval=] [–version]
For more options and how to use check watch man page
whereis - locate the binary, source, and manual page files for a command
Syntax
whereis [ -bmsu ] [ -BMS directory… -f ] filename …
For more options and how to use check whereis man page
wc - print the number of newlines, words, and bytes in files
Syntax
wc [OPTION]… [FILE]…
For more options and how to use check wc man page
xload - system load average display for X
Syntax
xload [-toolkitoption …] [-scale integer] [-update seconds] [-hl color] [-highlight color] [-remote host] [-jumpscroll pixels] [-label string] [-nolabel] [-lights]
For more options and how to use check xload man page