TESTING FOR BEGINNER: Basic UNIX Commands

cat --- for creating and displaying short files
chmod --- change permissions
cd --- change directory
cp --- for copying files
date --- display date
echo --- echo argument
ftp --- connect to a remote machine to download or upload files
grep --- search file
head --- display first part of file
ls --- see what files you have
lpr --- standard print command (see also print )
more --- use to read files
mkdir --- create directory
mv --- for moving and renaming files
print --- custom print command (see also lpr )
pwd --- find out what directory you are in
rm --- remove a file
rmdir --- remove directory> %
rsh --- remote shell
setenv --- set an environment variable
sort --- sort file
tail --- display last part of file
tar --- create an archive, add or extract files
telnet --- log in to another machine

cat

This is one of the most flexible Unix commands. We can use to create, view and concatenate files. For our first example we create a three-item English-Spanish dictionary in a file called "dict."

% cat >dict

test1

test2

test3

<control-D>

chmod

This command is used to change the permissions of a file or directory. For example to make a file new_file.pl readable by everyone, we do this:

% chmod a+r new_file.pl

To make a file, e.g., a shell script mycommand executable, we do this

% chmod +x mycommand

Now we can run mycommand as a command.

To check the permissions of a file, use ls -l . For more information on chmod, use man chmod.

Use cd to change directory. Use pwd to see what directory you are in.

% cd english

% pwd

% /test_file/test

% ls

scrapbook

% cd

Use cp to copy files or directories.

% cp test_file test_file.bk

This makes a copy of the file test_file.

% cp ~/new_file/new_file.bk

This copies the file jabber in the directory poems to the current directory. The symbol "." stands for the current directory. The symbol "~" stands for the home directory.

date

Use this command to check the date and time.

% date

Fri Nov 6 08:52:42 MST 2012

echo

The echo command echoes its arguments. Here are some examples:

grep

Use this command to search for information in a file or files. For example, suppose that we have a file dict whose contents are

redtest1
white test1

head

Use this command to look at the head of a file. For example,

% head test.pl

displays the first 10 lines of the file essay.001 To see a specific number of lines, do this:

% head -n 20 test.pl

This displays the first 20 lines of the file.

Use ls to see what files you have. Your files are kept in something called a directory.

% ls

test letter2

test1 letter3

test3 maple-assignment1

lpr

This is the standard Unix command for printing a file. It stands for the ancient "line printer." See

% man lpr

for information on how it works. See print for information on our local intelligent print command.

mkdir

Use this command to create a directory.

% mkdir test

Use this command to change the name of file and directories.

% mv foo foobar

The file that was named foo is now named foobar

print

This is a moderately intelligent print command.

% print foo

% print notes.ps

% print manuscript.dvi

pwd

Use this command to find out what directory you are working in.

% pwd

Use rm to remove files from your directory.

% rm test.pl

remove test.pl? y

% rm letter*

remove letter1? y

remove letter2? y

rmdir

Use this command to remove a directory. For example, to remove a directory called "essays", do this:

% rmdir essays

A directory must be empty before it can be removed. To empty a directory, use rm.

rsh

Use this command if you want to work on a computer different from the one you are currently working on. One reason to do this is that the remote machine might be faster. For example, the command

% rsh solitude

connects you to the machine solitude. This is one of our public workstations and is fairly fast.

sort

Use this commmand to sort a file. For example, suppose we have a file dict with contents

red test
white test1

tail

Use this command to look at the tail of a file. For example,

% tail new_test.pl

displays the last 10 lines of the file new_test.pl To see a specific number of lines, do this:

% tail -n 20 new_test.pl

This displays the last 20 lines of the file.

tar

Use create compressed archives of directories and files, and also to extract directories and files from an archive. Example:

% tar -tvzf test.tar.gz

displays the file names in the compressed archive foo.tar.gz while

% tar -xvzf test.tar.gz

extracts the files.

telnet

Use this command to log in to another machine from the machine you are currently working on. For example, to log in to the machine "solitude", do this:

% telnet solitude

Thursday 22 November 2012

Basic UNIX Commands