11. BASIC LINUX COMMANDS mkdir - make directories Usage mkdir [OPTION] DIRECTORY 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), not rwxrwxrwx - umask -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 information and exit

12. BASIC LINUX COMMANDS cd - change directories mv- change the name of a directory Ex: mv testdir newnamedir pwd - print working directory rmdir - Remove an existing directory rm -Removes directories and files within the directories recursively. chown - change file owner and group

13. Change the owner and/or group of each FILE to OWNER and/or GROUP. With --reference, change the owner and group of each FILE to those of RFILE. -c, changes like verbose but report only when a change is made -dereference affect the referent of each symbolic link, rather than the symbolic link itself -h, no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the ownership of a symlink)‏ -from=CURRENT_OWNER:CURRENT_GROUP change the owner and/or group of each file only if its current owner and/or group match those specified here. Either may be omitted, in which case a match is not required for the omitted attributes

14. - no-preserve-root do not treat `/' specially (the default)‏ -preserve-root fail to operate recursively on `/' -f, -silent, -quiet suppress most error messages -reference=RFILE use RFILE's owner and group rather than the specifying OWNER:GROUP values -R, -recursive operate on files and directories recursively -v, -verbose output a diagnostic for every file processed The following options modify how a hierarchy is traversed when the -R option is also specified. If more than one is specified, only the final one takes effect. -H if a command line argument is a symbolic link to a directory, traverse it -L traverse every symbolic link to a directory encountered -P do not traverse any symbolic links (default)‏ g - Group that owns the file.

15. 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 ls - Short listing of directory contents -a list hidden files -d list the name of the current directory

16. 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 cp - Copy files 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. 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". 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 & contents

17. BASIC LINUX COMMANDS n - Creates a symbolic link to a file. ln -s test symlink locate - A fast database driven file locator. slocate -u more - Allows file contents or piped output to be sent to the screen one page at a time less - Opposite of the more command 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. whereis - Report all known instances of a command wc - Print byte, word, and line counts. bg:

18. cal month year - Prints a calendar for the specified month of the specified year. cat files - Prints the contents of the specified files. clear - Clears the terminal screen. cmp file1 file2 - Compares two files, reporting all discrepancies. Similar to the diff command, though the output format differs. diff file1 file2 - Compares two files, reporting all discrepancies. Similar to the cmp command, though the output format differs. dmesg - Prints the messages resulting from the most recent system Boot. fg fg jobs - Brings the current job (or the specified jobs) to the foreground. file files - Determines and prints a description of the type of each specified file. find path -name pattern -print Searches the specified path for files with names matching the specified pattern (usually enclosed in single quotes) and prints their names. The find command has many other arguments and functions; see the online documentation. finger users - Prints descriptions of the specified users. free - Displays the amount of used and free system memory.

19. head files - Prints the first several lines of each specified file. ispell files - Checks the spelling of the contents of the specified files. kill process_ids kill - signal process_ids kill -l Kills the specified processes, sends the specified processes the specified signal (given as a number or name), or prints a list of available signals. killall program killall - signal program Kills all processes that are instances of the specified program or sends the specified signal to all processes that are instances of the specified program. mail - Launches a simple mail client that permits sending and receiving email messages. man title man section title - Prints the specified man page. ping host - Sends an echo request via TCP/IP to the specified host. A response confirms that the host is operational. reboot - Reboots the system (requires root privileges). shutdown minutes shutdown -r minutes Shuts down the system after the specified number of minutes elapses (requires root privileges). The -r option causes the system to be rebooted once it has shut down.

20. sort files - Sorts the specified files. The command has many useful arguments; see the online documentation. split file - Splits a file into several smaller files. The command has many arguments; see the online documentation sync - Completes all pending input/output operations (requires root privileges). telnet host - Opens a login session on the specified host. top - Prints a display of system processes that's continually updated until the user presses the q key. traceroute host - Uses echo requests to determine and print a network path to the host. uptime - Prints the system uptime. w - Prints the current system users. wall - Prints a message to each user except those who've disabled message reception. Type Ctrl-D to end the message.

21. ADVANCE LINUX COMMAND This page contains commands that are not essential for newbies but can be fun and/or very productive if you take the time to learn them. Above all, they can be very educational--linux is a great learning platform. There are thousands of free programs available on Linux, but some of them may be missing on your system, depending on your distribution. You can always find the hompage with google, and then download them. banner /usr/games/banner -w79 &quot;Happy Birthday, Marie&quot; > marie.txt Create an ascii &quot;banner&quot; with the width of 79 characters. The output is sent to file marie.txt. Script Log my current session in the text terminal into a text file typescript (the default filename). The log finishes when I type exit or press <Ctrl>d. Emacs (in X-terminal) The emacs text editor. Advanced and sophisticated text editor. Seems for gurus only: &quot;emacs is not just an editor, it is a way of living&quot;. Emacs surely seems rich or bloated, depending on your point of view. There are likely 3 versions of emacs installed on your system: (1) text-only: type emacs in a text (not X-windows) terminal (I avoid this like fire); (2) graphical-mode: type emacs in an X-windows terminal (fairly usable even for a newbie if you take some time to learn it); and (3) X-windows mode: type &quot;xemacs&quot; in an X-windows terminal.

22. khexedit (in X terminal) Simple hexadecimal editor. Another hexadecimal editor is hexedit (text based, less user friendly). Hex editors are used for editing binary (non-ASCII) files. diff file1 file2 > patchfile Compare contents of two files and list any differences. Save the output to the file patchfile. sdiff file1 file2 Side-by-side comparison of two text files. Output goes to the &quot;standard output&quot; which normally is the screen. patch file_to_patch patchfile Apply the patch (a file produced by diff, which lists differences between two files) called patchfile to the file file_to_patch. If the patch was created using the previous command, I would use: patch file1 patchfile to change file1 to file2. Regular expression(regexpr)‏ Sed Gaw k cvs Concurrent versions system. Try: info cvs for more information. Useful to keep the &quot;source code repository&quot; when several programmers are working on the same computer program. cervisia

23. file -z filename Determine the type of the file filename. The option -z makes file look also inside compressed files to determine what the compressed file is (instead of just telling you that this is a compressed file). To determine the type of content, file looks inside the file to find particular patterns in contents (&quot;magic numbers&quot;)--it does not just look at the filename extension like MS Windows does. The &quot;magic numbers&quot; are stored in the text file /usr/share/magic--really impressive database of filetypes. Touch file name strings filename | more Display the strings contained in the binary file called filename. &quot;strings&quot; could, for example, be a useful first step to a close examination of an unknown executable. wc (=word count) Print the number of lines, words, and bytes in the file. Examples: dir | wc cat my_file | wc wc myfil od

24. cksum filename Compute the CRC (=&quot;cyclic redundancy check&quot;) for file filename to verify its integrity. md5sum filename Compute a md5 checksum (128-bit) for file filename to verify its integrity. mkpasswd -l 10 Make a hard-to-guess, random password of the length of 10 characters. sort -f filename Arrange the lines in filename according to the ascii order. The option -f tells sort to ignore the upper and lower character case. The ascii character set is (see man ascii): Dec Hex Char Dec Hex Char Dec Hex Char Dec Hex Char uniq (=unique) Eliminate duplicate lines in sorted input. Example: sort myfile | uniq fold -w 30 -s my_file.txt > new_file.txt Wrap the lines in the text file my_file.txt so that there is 30 characters per line. Break the lines on spaces. Output goes to new_file.txt.

25. LINUX SET UP Linux: Setup as DNS Client / Name Server IP Address Many new Linux user finds it difficult to setup / modify new name server address (NS1 / NS2). Local name resolution is done via /etc/hosts file. If you have small network, use /etc/hosts file. DNS (domain name service is accountable for associating domain names with ip address, for example domain yahoo.com is easy to remember than IP address 202.66.66.12) provides better name resolution. To configure Linux as DNS client you need to edit or modify /etc/resolv.conf file. This file defines which name servers to use. You want to setup Linux to browse net or run network services like www or smtp; then you need to point out to correct ISP DNS servers: /etc/resolv.conf file In Linux and Unix like computer operating systems, the /etc/resolv.conf configuration file contains information that allows a computer connected to the Internet to convert alpha-numeric names into the numeric IP addresses that are required for access to external network resources on the Internet. The process of converting domain names to IP addresses is called &quot;resolving.&quot; The resolv.conf file typically contains the IP addresses of nameservers (DNS name resolvers) that attempt to translate names into addresses for any node available on the network.

26. Setup DNS Name resolution Steps to configure Linux as DNS client, first login as a root user (use su command): Step # 1: Open /etc/resolv.conf file: # vi /etc/resolv.conf Step #2: Add your ISP nameserver as follows: search isp.com nameserver 202.54.1.110 nameserver 202.54.1.112 nameserver 202.54.1.115 Note Max. three nameserver can be used/defined at a time. Step # 3:Test setup nslookup or dig command: $ dig www.nixcraft.com $ nslookup www.nixcraft.com