ps: check process status Syntax: ps ?option Option: e: list all currently running processes (A for Linux) f: gives full listing (give ancestry for Linux) l: gives long listing u username: list processes for the user only S: sleeping O: running R: on... Read More

Find command is used to search for a file with a specific file name in a set of files. Syntax: find .-name "fileE" -print grep command is used to search pattren within a file. Syntax: grep "pattren" filename Read More

man A filter is a program which can receive a flow of data from std input, process (or filter) it and send the result to the std output. Read More

cat filename | head -n | tail +k Read More

$od -cbd file_name c - character, b - binary (octal), d-decimal, od=Octal Dump. Read More

Zombie process: They do not take any up physical memory. Processes locked in memories that are updating the region of the process. Kernel swaps only the sleeping processes rather than the ?ready-to-run? processes, as they have the higher probability... Read More

rm -r * Read More

There are four possible results from this call: ?kill()? returns 0. This implies that a process exists with the given PID, and the system would allow you to send signals to it. It is system-dependent whether the process could be a zombie. ?kill()?... Read More

1. Output of who should be displayed on the screen with value of total number of users who have logged in displayed at the bottom of the list. 2. Output of ls should be displayed on the screen and from this output the lines containing the word ?poem?... Read More

A pipe is two or more commands separated by pipe char '|'. That tells the shell to arrange for the output of the preceding command to be passed as input to the following command. Example : ls -l | pr The output for a command ls is the... Read More

Yes, wc-stands for word count. wc -c for counting number of characters in a file. wc -l for counting lines in a file. Read More

cmp - Compares two files byte by byte and displays the first mismatch diff - tells the changes to be made to make the files identical Read More

$ ls > file1 $ banner hi-fi > message $ cat par.3 par.4 par.5 >> report $ cat file1>file1 $ date ; who $ date ; who > logfile $ (date ; who) > logfile Read More

With the help of kill command we can terminate the process. Syntax: kill pid Kill 0 - kills all processes in your system except the login shell. Read More

?grep? is a pattern search command. It searches for the pattern, specified in the command line with appropriate option, in a file(s). Syntax : grep Example : grep 99mx mcafile Read More

Sh is the command line interpreter and it is the primary user interface. This forms the programmable command line interpreter. After windows appeared it still retained the programmable characteristics. Read More

This command allows you to change, write, read and execute permissions on your file. Changes can be done to the file system but at times you need to change permissions for the file systems. At times files should be executable for viewing the files. Read More

This command is used to print a file. If you want to change the default print you can change the printer by using the P option. For double sided print you can use lpr-Pvalkyr-d. This is very useful command in UNIX present in many packages. Read More

This command finds files present anywhere on the system. This command is used to find document location where you forgot the directory in which you kept the file but you do remember about the name. This command is not restricted in finding files it... Read More

This command lets you download information, documents, etc from a remote ftp. First it is important to configure an FTP for the process to begin. Some of the important commands relevant to the usage of FTP are as follows get, put, mget, mput, etc. If... Read More

It reads the standard input and sends it to the standard output while redirecting a copy of what it has read to the file specified by the user. Read More

After the command line is terminated by the key, the shel goes ahead with processing the command line in one or more passes. The sequence is well defined and assumes the following order. Parsing: The shell first breaks up the command line into words,... Read More

Absolute path : Exact path from root directory. Relative path : Relative to the current path. Read More

Kill $! Read More

Yes, it stands for ?disk usage?. With the help of this command you can find the disk capacity and free space of the disk. Read More

Two prompts, PS1 (Primary Prompt), PS2 (Secondary Prompt). Read More

The input from a pipe can be combined with the input from a file . The trick is to use the special symbol ?-? (a hyphen) for those commands that recognize the hyphen as std input. In the above command the output from who becomes the std input to sort... Read More

Kernel checks 'type' field in the file's inode structure. Read More

Use ?su? command. The system asks for password and when valid entry is made the user gains super user (admin) privileges. Read More

is the output redirection operator when used it overwrites while >> operator appends into the file. Read More

$ echo * It is similar to 'ls' command and displays all the files in the current directory. Read More

Directing the flow of data to the file or from the file for input or output. Example : ls > wc Read More

Gzip filename is used to compress the files so that those files take up less space. The size of the file actually gets reduced to half their size but they might also depend upon about the file size and nature of the file systems. Files using gzip... Read More

This command is used to remove documents from the printer queue. The job number or the queue number can be found by using lpq. Printer name should be specified but this is not necessary if you want to use your default printer. Read More

This command lets you to send email message from your system. This command is not the only one which sends email there are lots of other messenger systems which can facilitate the process of sending a mail. This command behaves differently on... Read More

This command ends the process to which it was assigned (ID). This command cannot be used in multi systems in the network. ID can be obtained by the command ps. This command ignores completely the state at which the process is it kills the process. Read More

This command allows you to read the news. First you can read about the local news and then the remote news. "nnl? command makes or allows you to read local news and nnr command is used to read remote news. Manual and help information is available... Read More

Cat displays file contents. If the file is large the contents scroll off the screen before we view it. So command 'more' is like a pager which displays the contents page by page. Read More

Yes, ?mkfs? is used to create a new file system. Read More

ls stands for list; so it displays the list of the files that starts with 'chapter' with suffix '1' to '5', chapter1, chapter2, and so on. Read More

UNIX operating system originally was developed in 1969. This is an open source operating system developed by AT&T. It is widely used in work stations and servers. It is designed to be multi tasking, multi user and portable. UNIX has many several... Read More

This command is used to give information about the user; it gives out a profile about the user. This command is very useful for administrators as it gives the log information, email, current log information, etc. finger also displays information... Read More

Shell variables are special variables, a name-value pair created and maintained by the shell. Example: PATH, HOME, MAIL and TERM Read More

?inode?, each file has a separate inode and a unique inode number. Read More

Refer was written in Bell Laboratories and it is implemented as a troff preprocessor. This program is used managing bibliographic references and it is used to cite them in troff documents. It is offered in most of the UNIX packages. It refers with... Read More

UNIX systems were primarily used for typesetting systems and document formatting. Modern UNIX systems used packages such as Tex and Ghostscript. It uses some of the programs such as nroff, tbl, troff, refer, eqn and pic.Document formatting is very... Read More

Yes, using the ?mesg? command. Read More

There are two utilities they are system and user utilities. System utilities contain administrative tools such as mkfs, fsck, etc. Where as user utilities contain features such as passwd, kill, etc. It basically contains environment values. Read More

This command helps you to browse web from an ordinary terminal. Text can be seen but not the pictures. URL can be assigned as an argument to the G command. Help section can be obtained by pressing H and Q makes the program to quit. Read More