It's just picky about who it's friends are...''. -- Unknown, seen in .sigs around the world. Basics of the Unix/Linux Environment. Shells and Your Unix Environment. What is a shell?. Traditional user interface with the unix operating system…it interprets your typing . ID: 400563
DownloadNote - The PPT/PDF document "''Unix is user friendly --" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Presentations text content in ''Unix is user friendly --
Slide1
''Unix is user friendly --
It's just picky about who it's friends are...''
-- Unknown, seen in .sigs around the world
Slide2
Basics of the Unix/Linux Environment
Shells and Your Unix Environment
Slide3
What is a shell?
Traditional user interface with the unix operating system…it interprets your typing
A scripting program that controls the syntax at the command line interface
Just as there are many flavors of unix and unix-like systems, there are many types of shells
Slide4
Common Shells
Bourne
Shell
Bourne Again
Shell
TENEXC shell
C Shell
KornShell
Slide5
sh
Bourne shell
the original Unix shell
Pro: Flexible and powerful scripting shell
Con: Not interactive or particularly user friendly
Slide6
csh
C shell
designed for the BSD Unix system
syntax closely follows C programming
Pro: easy for C programmers to learn and comes with many interactive features such as file completion and aliases
Con: not as flexible or powerful a scripting language
Slide7
ksh
Korn
shell
derived from the Bourne shell so has a shared syntax
job control taken from the C shell
Slide8
bash
Bourne-Again shell
Combines the “best” of
sh
,
ksh
, and
csh
Default shell on Linux and Mac OSX operating systems
Pro: Flexible and powerful scripting language with all the interactive features of
csh
plus command completion
This shell is great for complicated GMT scripts
Slide9
tcsh
TENEX C shell
Default shell of the CERI unix environment
Pro: User friendly on the command line &
it is what your CERI account environment is set up to use
Con: It is not as suitable for long and involved scripts
It is perfectly good for most daily geophysics work on the command line & most faculty here use it on a daily basis so there are many experts around
Slide10
What is my shell?
env
$SHELL
will echo your current login shell to the screen
to switch your shell in a single terminal window, simply type the name of the preferred shell
the command line also usually indicates which shell family you are using
$ -- bash,
sh
, or
ksh
> or % --
csh
,
tcsh
Slide11
Useful features of tcsh & bash
file completion: you can key the tab button to complete the name of a long file
history
: list the previous commands entered during the active session
%
history
1139 11:19
ls
| more | tail -n5 >>
directory.list
up and down arrow keys: allow you to move up and down through previous commands
right and left arrow keys: allow you to edit command lines without starting from scratch
!XXX: reruns the command labeled XXX in the history list
%
!1139
ls
| more | tail -n5 >>
directory.list
Slide12
The Unix Environment
Mitch has set up the basic CERI environment so that everyone can access the standard geophysics packages available on the Sun system
But what does this mean?
your environment is composed of a number of
environment variables
which provide important information to the operating system
since you generally want the computer to behave the same way everyday, these environment variables are setup in configuration files accessed at login
Slide13
What are your environment variables?
env
: prints the current environment variables to the screen
Slide14
HOME & SHELL
HOME: this environment variable controls what other unix commands consider your base or home directory
this is how “%
cd
“ knows which directory to go to
%
echo $HOME
/
gaia/home/hdeshon
SHELL: this variable stores your default shell
%
echo $SHELL
/
usr/bin/tcsh
*these environment variables should not be changed by the user
Slide15
PATH
PATH: tells the shell where to find applications and/or executable files
on a command and the shell can’t find a manual page (and you are sure the man page exists), this environment variable may not be set correctly
Slide21
HOST & REMOTEHOST
HOST: the name of the machine you are currently logged into
REMOTEHOST: the name of the machine you are sitting in front of, if different
%
echo $HOST $REMOTEHOST
enigma sailfish2.ceri.memphis.edu
Slide22
SSH Related Variables
SSH_CLIENT: the IP (internet protocol) address of the HOST machine
SSH_CONNECTION: the IP address of the HOST machine and the REMOTEHOST machine
%
echo $SSH_CLIENT $SSH_CONNECTION
141.225.156.223 52372 22
141.225.156.223 52372 141.225.157.75 22
Slide23
Modifying your current shell environment
If you mess up modifying the environment in your current window – you may “break” your current window (shell).
This is generally not a problem on the sun,
mac
, etc.
The environment is local to that window/shell.
Just close it and open another window.
Slide24
set
set
: sets
csh
shell variables
A typical
tcsh
set
command is
%
set history=100
This would save the last 100 commands on the history list.
The bash equivalent is simply
%history=100
Slide25
setenv
setenv
: the csh command to change environment settings.
%
setenv
PATH {$PATH}:/
gaia/home/hdeshon/scripts
this adds the directory ‘~/scripts’ to the
end of the environment
variable PATH within the active window
The bash equivalent is simply
%PATH=$PATH:/
gaia/home/hdeshon/scripts
Slide26
s
etenv
c
an
be run on the command line, from within a local configuration file (.
cshrc
or .login), or in a shell script.
When run without specifying an environment variable, it will print all environment variables to the screen
Slide27
Making your own environment variables
Anytime you want a global definition of something, you can create your own global environment variable
%
setenv
LATESTRTVEL rtvel4_9305_5bv19
Slide28
Modifying your default environment
It will get old changing everything to the way you want it each time you log in/open a new window/start a new shell. And this being Unix, there is a (easy) way to set up your own personal environment.
The setup of your personal environment (personal changes/preferences for how you want the shell to work for you) is stored in shell configuration files, aka dot files
.
cshrc
or .
bashrc
There is also a file .login, but it is not likely you will have to change it (it get’s used when you log in, not each time you start a shell)
Slide29
setenv PATH ${PATH}:/gaia/home/hdeshon/scriptssetenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:/gaia/home/hdeshon/fftw-2.1.5/libsetenv PRINTER 3876_gradset filec #explicitly turns on file completionset noclobber #turns on no clobber, which keeps redirect > from #overwriting files unless the ! is specifiedset history=500 #keep the last 500 commands in the history listalias l 'ls -F'
If you need to modify your environment configuration file (.
cshrc
, .
bashrc
), do so with care
Always leave two terminal windows open (prior to making any changes) in case you mess your file up so completely and break your active window, you have another window open to delete the offending file
Always backup the file you before modifying it!
Slide32
Aliases
alias
: creates a pseudonym or nickname for a common command or series of commands
Anything you find yourself typing repeatedly can be set to an alias
Anything you find yourself frequently
mis
-typing can be set to an alias
unalias
: unset the alias
alias
and
unalias
can be run within a terminal window for short-term usage or set in your configuration files for long-term usage
Slide33
Aliases examples
alias
settitlebar
'echo -n "^[]2;$CWD^G"'
alias
cwdcmd
'set PROMPT="[${
USER}@`hostname
`] $CWD% "'
alias
cd
'
chdir
\!* &&
cwdcmd
&&
settitlebar
’
alias
howmuch
'du -
sk
.’
alias
h
'history’
alias
m
more
alias
mroe
more
alias
l
'
ls
-F'
alias
c
clear
alias
src
source
Slide34
Source
source
: executes configuration files
If you change your configuration file, you will need to execute the changes in all open terminal windows for the changes to take effect. They automatically will take effect when new terminal windows are opened.
Download this presentation
DownloadNote - The PPT/PDF document "''Unix is user friendly --" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Presentations text content in ''Unix is user friendly --
''Unix is user friendly --
It's just picky about who it's friends are...''
-- Unknown, seen in .sigs around the world
Slide2Basics of the Unix/Linux Environment
Shells and Your Unix Environment
Slide3What is a shell?
Traditional user interface with the unix operating system…it interprets your typing
A scripting program that controls the syntax at the command line interface
Just as there are many flavors of unix and unix-like systems, there are many types of shells
Slide4Common Shells
Bourne
Shell
Bourne Again
Shell
TENEXC shell
C Shell
KornShell
Slide5sh
Bourne shell
the original Unix shell
Pro: Flexible and powerful scripting shell
Con: Not interactive or particularly user friendly
Slide6csh
C shell
designed for the BSD Unix system
syntax closely follows C programming
Pro: easy for C programmers to learn and comes with many interactive features such as file completion and aliases
Con: not as flexible or powerful a scripting language
Slide7ksh
Korn
shell
derived from the Bourne shell so has a shared syntax
job control taken from the C shell
Slide8bash
Bourne-Again shell
Combines the “best” of
sh
,
ksh
, and
csh
Default shell on Linux and Mac OSX operating systems
Pro: Flexible and powerful scripting language with all the interactive features of
csh
plus command completion
This shell is great for complicated GMT scripts
Slide9tcsh
TENEX C shell
Default shell of the CERI unix environment
Pro: User friendly on the command line &
it is what your CERI account environment is set up to use
Con: It is not as suitable for long and involved scripts
It is perfectly good for most daily geophysics work on the command line & most faculty here use it on a daily basis so there are many experts around
Slide10What is my shell?
env
$SHELL
will echo your current login shell to the screen
to switch your shell in a single terminal window, simply type the name of the preferred shell
the command line also usually indicates which shell family you are using
$ -- bash,
sh
, or
ksh
> or % --
csh
,
tcsh
Slide11Useful features of tcsh & bash
file completion: you can key the tab button to complete the name of a long file
history
: list the previous commands entered during the active session
%
history
1139 11:19
ls
| more | tail -n5 >>
directory.list
up and down arrow keys: allow you to move up and down through previous commands
right and left arrow keys: allow you to edit command lines without starting from scratch
!XXX: reruns the command labeled XXX in the history list
%
!1139
ls
| more | tail -n5 >>
directory.list
Slide12The Unix Environment
Mitch has set up the basic CERI environment so that everyone can access the standard geophysics packages available on the Sun system
But what does this mean?
your environment is composed of a number of
environment variables
which provide important information to the operating system
since you generally want the computer to behave the same way everyday, these environment variables are setup in configuration files accessed at login
Slide13What are your environment variables?
env
: prints the current environment variables to the screen
Slide14HOME & SHELL
HOME: this environment variable controls what other unix commands consider your base or home directory
this is how “%
cd
“ knows which directory to go to
%
echo $HOME
/
gaia/home/hdeshon
SHELL: this variable stores your default shell
%
echo $SHELL
/
usr/bin/tcsh
*these environment variables should not be changed by the user
Slide15PATH
PATH: tells the shell where to find applications and/or executable files
%
echo $PATH
/gaia/smeagol/local/passcal.2006/bin:/gaia/smeagol/local/gmt/GMT4.2.1/bin:/opt/local/bin:/opt/local/sbin:/opt/csw/bin:/opt/csw/sbin:/ceri/local/bin:/usr/sbin:/ceri/local/sbin:/gaia/home/stbisrat/bin:/usr/local/bin:/opt/Studio/SUNWspro/bin:/opt/Studio/SUNWspro/prod/bin:/opt/sfw/bin:/usr/bin:/usr/dt/bin:/usr/openwin/bin:/bin:/usr/ucb:/usr/ccs/bin:/usr/local/teTeX/bin/sparc-sun-solaris2.8:/gaia/smeagol/local/bin
The : is used to separate each full path name
When a command is called from the command line, the shell will search through this list of paths, in order, until it finds the first instance
Slide16How does PATH work?
If you are working a program to do least squares analysis and decide to call it “
ls
,” what will happen when you enter the command “
ls
”?
It depends on your PATH variable.
When the shell goes looking through your path for an
executable
file named “
ls
”, it will run the first one it finds.
Slide17If the directory containing your least squares program (executable file), “
ls
”, is in your path
Before
the directory containing the Unix list command, “
ls
”, it will run your program and you will not be able (at least simply) to get a listing of your directory!
Slide18If the directory containing your least squares program, “
ls
”, is in your path
AFTER
the directory containing the Unix list command, “
ls
”, it will run the Unix
ls
command and you will not be able (at least simply) to run your program!
Slide19To force your least squares
executable in the current (working) directory
to run
%./
ls
To force the
unix
ls
command to run
%/bin/
ls
Slide20MANPATH
MANPATH: tells the shell where to find the manual pages read using the
man
command
%
echo $MANPATH
/gaia/smeagol/local/passcal.2006/man:/gaia:smeagol/local/gmt/GMT4.2.1/man:/opt/local/man:/ceri/local/man:/usr/dt/man:/usr/man:/usr/openwin/share/man:/usr/local/man:/opt/SUNWspro/man:/opt/sfw/man:/usr/local/teTeX/man:/gaia/smeagol/local/man:/opt/csw/man
If you do a
man
on a command and the shell can’t find a manual page (and you are sure the man page exists), this environment variable may not be set correctly
Slide21HOST & REMOTEHOST
HOST: the name of the machine you are currently logged into
REMOTEHOST: the name of the machine you are sitting in front of, if different
%
echo $HOST $REMOTEHOST
enigma sailfish2.ceri.memphis.edu
Slide22SSH Related Variables
SSH_CLIENT: the IP (internet protocol) address of the HOST machine
SSH_CONNECTION: the IP address of the HOST machine and the REMOTEHOST machine
%
echo $SSH_CLIENT $SSH_CONNECTION
141.225.156.223 52372 22
141.225.156.223 52372 141.225.157.75 22
Slide23Modifying your current shell environment
If you mess up modifying the environment in your current window – you may “break” your current window (shell).
This is generally not a problem on the sun,
mac
, etc.
The environment is local to that window/shell.
Just close it and open another window.
Slide24set
set
: sets
csh
shell variables
A typical
tcsh
set
command is
%
set history=100
This would save the last 100 commands on the history list.
The bash equivalent is simply
%history=100
Slide25setenv
setenv
: the csh command to change environment settings.
%
setenv
PATH {$PATH}:/
gaia/home/hdeshon/scripts
this adds the directory ‘~/scripts’ to the
end of the environment
variable PATH within the active window
The bash equivalent is simply
%PATH=$PATH:/
gaia/home/hdeshon/scripts
Slide26s
etenv
c
an
be run on the command line, from within a local configuration file (.
cshrc
or .login), or in a shell script.
When run without specifying an environment variable, it will print all environment variables to the screen
Slide27Making your own environment variables
Anytime you want a global definition of something, you can create your own global environment variable
%
setenv
LATESTRTVEL rtvel4_9305_5bv19
Slide28Modifying your default environment
It will get old changing everything to the way you want it each time you log in/open a new window/start a new shell. And this being Unix, there is a (easy) way to set up your own personal environment.
The setup of your personal environment (personal changes/preferences for how you want the shell to work for you) is stored in shell configuration files, aka dot files
.
cshrc
or .
bashrc
There is also a file .login, but it is not likely you will have to change it (it get’s used when you log in, not each time you start a shell)
Slide29setenv PATH ${PATH}:/gaia/home/hdeshon/scriptssetenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:/gaia/home/hdeshon/fftw-2.1.5/libsetenv PRINTER 3876_gradset filec #explicitly turns on file completionset noclobber #turns on no clobber, which keeps redirect > from #overwriting files unless the ! is specifiedset history=500 #keep the last 500 commands in the history listalias l 'ls -F'
.
cshrc
Slide30PATH=/usr/local/sod-2.2.2/bin:$ANTELOPE/bin:$PATHexport PATH
.
bashrc
Slide31some warnings
If you need to modify your environment configuration file (.
cshrc
, .
bashrc
), do so with care
Always leave two terminal windows open (prior to making any changes) in case you mess your file up so completely and break your active window, you have another window open to delete the offending file
Always backup the file you before modifying it!
Slide32Aliases
alias
: creates a pseudonym or nickname for a common command or series of commands
Anything you find yourself typing repeatedly can be set to an alias
Anything you find yourself frequently
mis
-typing can be set to an alias
unalias
: unset the alias
alias
and
unalias
can be run within a terminal window for short-term usage or set in your configuration files for long-term usage
Slide33Aliases examples
alias
settitlebar
'echo -n "^[]2;$CWD^G"'
alias
cwdcmd
'set PROMPT="[${
USER}@`hostname
`] $CWD% "'
alias
cd
'
chdir
\!* &&
cwdcmd
&&
settitlebar
’
alias
howmuch
'du -
sk
.’
alias
h
'history’
alias
m
more
alias
mroe
more
alias
l
'
ls
-F'
alias
c
clear
alias
src
source
Slide34Source
source
: executes configuration files
If you change your configuration file, you will need to execute the changes in all open terminal windows for the changes to take effect. They automatically will take effect when new terminal windows are opened.
%
nedit
~/.
cshrc
you’ve used
NEdit
to make file changes
%
source ~/.
cshrc
Slide35