Description:
You can
use the ls command to list the files in a directory.
Syntax:
# ls [option]
directory_name
Useful options:
-a : list all files
-s : list size (in how many 512K blocks)
-l : list in long format
-C : show in columns (default)
Making Directories
Name:
mkdir
Description:Create
the Directory(ies), if they do not already exist.
Syntax:
# mkdir directory_name
Changing to
a different directory
Name:
cd
Description:To
change your current working directory.
Syntax:
# cd pathname
Pathnames
Name:
pwd
Description:To
display the pathname to your current directory.
Syntax:
# pwd
Copying Files
/ Directories
Name:
cp
Description:To
copy a directory or a file.
Syntax:
# cp -r directory1
directory2
# cp file1 file2
Note: Here
the -r option for recursive copy.
Moving
Files / Directories
Name:
mv
Description:To
move files and directories from one place to another.
Syntax:
# mv [option]
file1 file2
# mv [option]
directory1 directory2
# mv [option]
file directory
Removing files
and directories
Name:
rm , rmdir
Description:To
remove files and directories.
Syntax:
# rm file_name
# rmdirdirectory
Note:The
directory must be empty before deleting it. You will need to remove
any files and subdirectories that it contains. To remove a directory
that contains files or subdirectories use the command:
# rm -rdirectory
Displaying the
contents of a file on the screen
Name:
cat
Description:The
cat command is useful for displaying short files of a few lines.
To display longer files use an editor or pager.
Syntax:
# cat file_name
Note: The
cat command can also be used to concatinate 2 files:
# cat file1
file2 > file3
Name:
vi
Description:The
vi editor (pronounced "vee eye") is available on all
UNIX systems: other editors are not. Being able to use vi ensures
that you will always have an editor available to you.
Description:A
pager is a program for displaying the contents of a text file
one screenful at a time. The most commonly used pager programs
are more and less. A Pager is a filter.
Syntax:
# more file_name
You can now use one
of the following commands:
space bar
Display next screenful of text. <RETURN> Display next line of text. q Exit from more: this can be done at any time. d Scroll forwards about half a screenful of text. b Skip backwards one screenful of text. h Display a list of commands (help).
# less file_name
Name:
head, tail
Description:To
display the first 10 lines of a text file use head. And to display
the last 10 lines of a text file use the command tail.
Syntax:
# head file_name
Options:
-n <NUMBER>
: To print
first NUMBER lines instead of first 10.
# tail file_name
Command History
Name:
history
Description: List history of last 15 commands used.
Syntax:
# history
Example
history
With no options,it displays the history list with line
numbers.
Searching the
contents of a file
Name:
grep
Description:To
search a text file for a string of characters or a regular expression.
Syntax:
# grep [option]
pattern file_name
Useful options:
-i ignore upper/lower case distinctions
-v display those lines that do NOT match
-n precede each maching line with the line number
-c print only the total count of matched lines
-r recursive [linux only]
Getting Help
Name:
man
Description:Type
man command to read the manual page for a particular command.
Syntax:
# man command_name
File system
security (access rights)
Each file (and directory)
has associated access rights, which may be found by typing 'ls
-l'.
# ls -l
You will see that you
now get lots of details about the contents of your directory,
similar to the example below.
Access rights
on files. r (or -), indicates read permission (or otherwise),
that is, the presence or absence of permission to read and copy
the file w (or -), indicates write permission (or otherwise),
that is, the permission (or otherwise) to change a file x (or -), indicates execution permission (or
otherwise), that is, the permission to execute a file, where appropriate
Access rights
on directories. r allows users to list files in the directory;
w means that users may delete files from the
directory or move files into it; x means the right to access files in the directory.
This implies that you may read files in the directory provided
you have read permission on the individual files.
Changing access rights
Name:
chmod
Description:To
change the access permissions for a file or directory.
Syntax:
# chmod modefile_name
#
chmod modedirectory_name
Note:
More details about mode:
There is a shorthand
way of setting permissions by using octal numbers. Read permission
is given the value 4, write permission the value 2 and execute
permission 1.
r w x
4 2 1
These values are added
together for any one user category:
1 = execute only
2 = write only
3 = write and execute (1+2)
4 = read only
5 = read and execute (4+1)
6 = read and write (4+2)
7 = read and write and execute (4+2+1)
So access permissions
can be expressed as three digits. For example:
user
group
others
(world)
chmod
640
file
rw-
r--
---
chmod
754
file
rwx
r-x
r--
chmod
664
file
rw-
rw-
r--
Processes and
Jobs
Name:
ps
Description:To
monitor the state of your processes.
Syntax:
# ps [-options]
Note:
The information displayed by the ps command varies acccording
to which command option(s) you use and the type of UNIX that you
are using.
Example: These are
some of the column headings displayed by the following command:
Here "| more"
is used to filter the output to 'more'.
Email message utility
Name:
pine
Description:Program for Internet News & Email - is a tool for reading, sending, and managing electronic
messages
Syntax:
# pine
Name:
jobs
Description:To
display the state of any background jobs that you are currently
running use the job command.
Syntax:
# jobs
Example1: To displays
the job number, its state and the command associated with this
job.
#!/bin/csh -f
# Clear the DISPLAY.
unsetenv DISPLAY
# Call MATLAB with the appropriate input and output,
# make it immune to hangups and quits using ''nohup'',
# and run it in the background.
nohup matlab < $1 > $2 &
# unsetenv DISPLAY
# nohup matlab
< input_file > output_file &
Bring a job into
the foreground
Name:
fg
Description:To
bring a specific background job into the foreground.
Syntax:
# fg job_number
For example: To bring
the third job which is running in the background:
Description:Each
process you start is usually completed within a few seconds. Sometimes
a background process or a process without a controlling terminal
hangs up and you will need to destroy this process by killing
it.
Syntax:
# kill [-signal]
process_identifier(PID)
Working:
Use the ps
-ef command if you need to find the PID of a process.
Always try to kill
a process with a simple kill command.
# kill process_identifier
This is the cleanest
way to kill a process and has the same effect as cancelling a
process.
If this does not work
use the -1 (one) signal.
# kill -1 process_identifier
This tells the process
to hangup just as though you were logging out. The system will
attempt to kill any child processes.
As a last resort use
the -9 signal:
# kill -9 process_identifier
This will stop the
process dead in its tracks but it may leave any child processes
still running.
A few other added features of kill command are:
# kill ^C
This will kill the current process - the one in the foreground
# kill ^Z
This will suspend foreground process.
Finding a file
Name:
find
Description:
To locate a file in the file system , use the find command.
Syntax:
# find path_name
-name file_name -print
Example:
# find . -name
"*.ps" -print
The above example search
current and all sub-directories for all .ps (postscript) files.
Note1: * = Wild
Char
Note2: . = Current
directory
Determine file type
Name:
file
Description:
Determines the type of content, "file" looks inside
the file to find particular patterns in contents
Syntax:
# file
Example:
# file -z attachment3.doc
In the above example option -z makes "file" look also inside
compressed files to determine what the compressed file is and determines the type of file attachment3.doc.
Compressing a
file
Name:
tar
Description:To
create an archive file or directory use the command.
Syntax:
# tar cvf tarfile_name.tarfile_names(directory_name)
Name:
zip
Description:zip
is a compression and file packaging utility for Unix, VMS, MSDOS,
OS/2, Windows NT, Minix, Atari and Macintosh, Amiga and Acorn
RISC OS.
Syntax:
# zip file_name
Name:
gzip
Description:To
compress a file to *.gz format. Usually used to further compress
the *.tar file.
Syntax:
# gzip [-options]
file_name
Note:
More about gzip is obtained by using the command "man gzip".
Name:
bzip2
Description:To
compress a file to *.bz2 format. Usually used to further compress
the *.tar file. This is the best compressing tool of all.
Syntax:
# bzip2 [-options]
file_name
Note: More
about bzip2 is obtained by using the command "man bzip2".
Name:
compress
Description:Compress
reduces the size of the named files ( *.Z format).
Syntax:
# compress [-options]
file_name
Note: More
about compress is obtained by using the command "man compress".
ADVANCED COMPRESSION:
# tar czf file_name.tgzfile_names(directory_name)
# tar cjf file_name.tgzfile_names(directory_name)
Uncompressing
a file
Name: tar
Description:To
unpack a tar file use the tar command.
Syntax:
# tar xvf tarfile_name.tar
Name:
unzip
Description:To
unzip a zip file.
Syntax:
# unzip file_name
Name:
bunzip2
Description:To
decompress *.bz2, *.bz, *.tbz2, *.tbz format files.
Syntax:
# bunzip2file_name
Note: bunzip2
will decompress the files to following format:
Description:
gunzip can currently decompress files created by gzip, zip, compress
or pack. Simillarly use uncompress for *.Z files.
Syntax:
# gunzip [-options]
file_name
# uncompress
[-options]
file_name
Advanced Uncompressing
.tgz and .bz2
# tar zxf file_name.tgz
# tar jxf file_name.bz2
or in Solaris:
# gzcat file_name.tar.gz
| tar xf -
# bzcat file_name.tar.bz2
| tar xf -
Transferring
files
Name:
sftp
Description:Secure
file transfer over the network. To transfer a file/directory use
the sftp command.
Syntax:
# sftp user_name@remote_host
Note: You
will be prompted to enter the password for that remote_host. After
entering the password you will get the following prompt:
sftp>
Example:
To use file pathnames
to define both the local-file and the remote-file:
sftp> putREPORTS/april reports/month4
This copies the contents
of the file april in the sub-directory REPORTS, which is in your
current directory on the local host to the file month4 in the
sub-directory reports, which is in your login directory on the
remote host.
Simillarly:
To get a file from
a subdirectory on the remote host:
sftp> get
reports/quarterly/march tmp/month3
This transfers a copy
of the file march in the remote subdirectory reports/quarterly
to the local filename month3 in the subdirectory tmp.
To get more options
try:
sftp> help
Name:
scp
Description:To
transfer a file/directory you can also use scp (secure copy client).
Example: To copy a
file from local host directory "/etc/export/example"
to remote computer "mathhost.asu.edu" with user name
"user" and to location "/ud/user/stuff" use
the following command:
Note1: To
get the names of the printer you have access to, use the following
command:
#
lpstat -s
Example:
#
lpstat -s
scheduler is running
system default destination: lp
system for lp: localhost
system for c: localhost
# lp -P c example.txt
Note2: To
print on both sides if the printer support duplex printing:
# lpr -Z duplex
<file to print>
Word,
Line and Character count
Name: wc
Description:Print byte, word, and newline counts for each FILE, and a total line if
more than one FILE is specified. With no FILE, or when FILE is -, read
standard input.
Syntax:
# wc [option]
file1 file2
# wc [option]
-
Useful options:
-c, --bytes : print the byte counts
-m, --chars : print the character count
-l, --lines : print the newline counts
-w, --words : print the word counts
Changing the priority of the Job
Name: nice
Description:Run COMMAND with an adjusted scheduling priority. With no COMMAND,
print the current scheduling priority. ADJUST is 10 by default. Range goes from -20 (highest priority) to 19 (lowest).
Syntax:
# nice [option] [command [arg] . . .]
Finding out who has logged on
Name: who
Description:Display
information about the current system users.
Syntax:
# who [option] file1
# who [option] arg1 arg2
Sorts contents of a file
Name: sort
Description: Write sorted concatenation of all FILE(s) to standard output.
Syntax:
# sort [option] file1
Clear the Screen
Name: clear
Description:Clear the screen.
Syntax:
# clear
Shows the time and date
Name: date
Description:Print or set system date and time.
Syntax:
# date [option]
[MMDDhhmm] [[CC]YY][.ss]]
The date can be displayed as the above format:
MM : month of the year
DD : day of the month
hh : hour of the day
mm : minutes passed of an hour
CC : century
YY : year
Prints a
summary of total space occupied by all files in a hierarchy
Name: du
Description:
This command shows you the size of your subdirectories in kilobytes
Syntax:
du [option]
Example:
#du -s *
This command is used summarize the disk use of all the files and
directories in home directories
Forwarding
your mail from Math and Mathpost server
Apply the following
steps to forward you email from math or mathpost server to other
email servers:
In your home directory
create a file called ".forward"
Open the file using
vi editor or any other editor of your choice.
Type the email address
to which you want to forward your email.
Example:
# vi .forward
xyz@yahoo.com
Save the file and your email will be forwarded to xyz@yahoo.com.
