Environment Setup

From DreamHost

When installing in your home directory, you will need to change the environment variables for the installation to work.

Contents 1 Temporary session 2 Bash Files 3 Shell Commands 4 Setting a user-friendly prompt 4.1 Helpful Power Prompts 5 Setting a Login Message 6 Add color to directory listing 7 Editing Your Environment Profile 8 If you use the .bash_profile 9 Directory Clutter 10 Disabling New Email Notifications 11 Changing your timezone 12 See Also 13 External Links

Temporary session

In most cases, the change to setup environment should be temporary and once an installation is finished, it should be changed back for programs to run correctly. The reason that programs may fail is in LD_LIBRARY_PATH variable set to make installed software find libraries not present by default on DreamHost server. In case of newer version of there libraries with fixed bugs appear on DreamHost it could happen that your forgotten libraries will be used instead. It is not advisable to use LD_LIBRARY_PATH variable in production.

Bash Files

When logging into an interactive login shell, login will do the authentication, set the environment and start your shell. In the case of bash, the next step is reading the general profile from /etc, if that file exists. bash then looks for ~/.bash_profile, ~/.bash_login and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. If none exists, /etc/bashrc is applied.

Shell Commands

export LD_LIBRARY_PATH=$HOME/lib/
export PATH="$HOME/bin:$PATH"
source ~/.bash_profile

Setting a user-friendly prompt

Just change the PS1 variable in your ~/.bash_profile file. To see changes immediately after saving, run

. ~/.bash_profile

When executing interactively, bash displays the primary prompt PS1 when it is ready to read a command, and the secondary prompt PS2 when it needs more input to complete a command. Bash allows these prompt strings to be customized by inserting a number of backslash-escaped special characters that are decoded as follows:

\a     an ASCII bell character (07)
\d     the date in "Weekday Month Date" format (e.g., "Tue May 26")
\D{format}  the format is passed to strftime(3) and the result is inserted into the prompt string; an empty format results in a locale-specific time representation.
\e     an ASCII escape character (033)
\h     the hostname up to the first `.'
\H     the hostname
\j     the number of jobs currently managed by the shell
\l     the basename of the shell's terminal device name
\n     newline
\r     carriage return
\s     the name of the shell, the basename of $0 (the portion following the final slash)
\t     the current time in 24-hour HH:MM:SS format
\T     the current time in 12-hour HH:MM:SS format
\@     the current time in 12-hour am/pm format
\A     the current time in 24-hour HH:MM format
\u     the username of the current user
\v     the version of bash (e.g., 2.00)
\V     the release of bash, version + patchelvel (e.g., 2.00.0)
\w     the current working directory
\W     the basename of the current working directory
\!     the history number of this command
\#     the command number of this command
\$     if the effective UID is 0, a #, otherwise a $
\nnn   the character corresponding to the octal number nnn
\\     a backslash
\[     begin a sequence of non-printing characters, which could be used to embed a terminal control sequence into the prompt
\]     end a sequence of non-printing characters

The command number and the history number are usually different: the history number of a command is its position in the history list, which may include commands restored from the history file, while the command number is the position in the sequence of commands executed during the current shell session. After the string is decoded, it is expanded via parameter expansion, command substitution, arithmetic expansion, and quote removal.

Helpful Power Prompts

export PS1='\[\033[1;33m\]\u\[\033[1;37m\]@\[\033[1;32m\]\h\[\033[1;37m\]:\[\033[1;31m\]\w \[\033[1;36m\]\$ \[\033[0m\]'
user@host:~/bin/tools $

export PS1="\e[1;31m[\h]$NC \W > \[\033]0;\${TERM} [\u@\h] \w\]"
[lifesaver] tools >

export PS1="\n\e[1;37m[\e[0;32m\u\e[0;35m@\e[0;32m\h\e[1;37m]\e[1;37m[\e[0;31m\w\e[1;37m]\n$ \e[0m"
[user@host][~/bin/tools]
$

export PS1="\n[$?]\e[1;37m[\e[0;32m\u\e[0;35m@\e[0;32m\h\e[1;37m]\e[1;37m[\e[0;31m\w\e[1;37m]($SHLVL:\!)\n\[\033[0m\]\$ "
[0][user@host][~/bin/tools](1:2130)

If you find yourself completely forgetting who and where you are, you can be constantly reminded by including user@hostname with:

export PS1='[\u@\h:\w]\$ '

Setting a Login Message

Just add code to execute to your ~/.bash_profile and it will run when an interactive shell logs in.

# Showing the DreamHost Message of the Day
head -n 7 /etc/motd|tail -n 6

# Showing ascii text
figlet -f smslant DreamHost

# Printing a calendar for the month
cal $(date +"%m") $(date +"%Y")

# Display Historic events that happened on this day
sed = $(echo /usr/share/calendar/calendar*) | sed -n "/$(date +%m\\/%d\\\|%b\*\ %d)/p"

# Display a riddle, literature snippet, or fortune
/usr/games/fortune -s

# Display machine stats
echo -e "Machine stats"; uptime
procinfo|head -n 13|tail -n 11

Add color to directory listing

You can get color output from your shell to differentiate between files, directories, links, archives, etc.

Shell command:

vim ~/.bash_profile

Copy this code into ~/.bash_profile:

# enable color support of ls and also add handy aliases
if [ "$TERM" != "dumb" ]; then
    eval "`dircolors -b`"
    alias ls='ls --color=auto'
    #alias rm 'mv \!* ~/TRASH'
    #alias dir='ls --color=auto --format=vertical'
    #alias vdir='ls --color=auto --format=long'
fi

Editing Your Environment Profile

Shell Command:

vi ~/.bashrc

Add the following to the file.

export PATH=~/bin:$PATH

If you use the .bash_profile

Shell Command:

vi ~/.bash_profile

Add the following to the file.

. .bashrc

Type the following in the shell prompt to load the new changes.

. .bashrc

Directory Clutter

If you use the above commands you will have a lot of folders created on your home directory. If you don't like that then you can create a folder.

mkdir packages

Then set the PATH and LD_LIBRARY_PATH to include the new directory.

export LD_LIBRARY_PATH=$HOME/packages/lib/
export PATH="$HOME/packages/bin:$PATH"

A complete shell account setup based in this idea is explained also in Unix account setup. That setup is used in other how-to's in this wiki.

Disabling New Email Notifications

Add the following to .bash_profile.

unset MAILCHECK

Then log out and log back in again.

Changing your timezone

You may be confused when your environment reports that the time is something different than what your kitchen clock says. You can move to Los Angeles (where the Dreamhost resides) but there's an easier way to get the two to match. Type in

tzselect

at the prompt and you'll be given instructions on how to configure your .bash_profile (or .bashrc) to your own timezone.

See Also

• UNIX commands
• Bash
• Unix account setup
• SSH
• Shell

External Links

• Bash Prompt HOWTO Official tldp.org HOWTO
• Bash FAQ
• Bash home page
• Advanced Bash-Scripting Guide