setting and displaying variables

Shell Programming and Scripting
1

Hello, I need a little help.

  1. Edit /etc/profile so that all users are greeted upon login.
  2. For the root account, set the prompt to something like "Danger!! root is doing stuff in \w", preferably in a bright color such as red or pink or in reverse video mode.

Thanks for help.

2

Is this homework?

/etc/profile is a shell script, so if you want to echo something, echo something . You can tell different users apart with the USER variable, if set. If it's not set, don't bother doing anything since you might be injecting 'Hi everybody!' into somebody's cron job or something equally pointless.

3

Assuming this is unix.
The convention is to put the message in the file /etc/motd (Message of the Day).
Check your /etc/profile file because most of the manufacturer supplied versions of /etc/profile look for the Message of the Day file. Don't forget to undo the change when you have finished.

Change the root prompt at your own risk. Remember that whoever logs in as root may not be using the same type of terminal as you!

4

No, it is not my homework. It is a bash practice problem from
Bash Guide for Beginners
I am using Linux fedora 14. I just want to improve myself.

Thanks.

---------- Post updated at 11:43 AM ---------- Previous update was at 11:35 AM ----------

How to modify profile?

# /etc/profile

# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc

# It's NOT good idea to change this file unless you know what you
# are doing. Much better way is to create custom.sh shell script in
# /etc/profile.d/ to make custom changes to environment. This will
# prevent need for merging in future updates.

pathmunge () {
    case ":${PATH}:" in
        *:"$1":*)
            ;;
        *)
            if [ "$2" = "after" ] ; then
                PATH=$PATH:$1
            else
                PATH=$1:$PATH
            fi
    esac
}


if [ -x /usr/bin/id ]; then
    if [ -z "$EUID" ]; then
        # ksh workaround
        EUID=`id -u`
        UID=`id -ru`
    fi
    USER="`id -un`"
    LOGNAME=$USER
    MAIL="/var/spool/mail/$USER"
fi

# Path manipulation
if [ "$EUID" = "0" ]; then
    pathmunge /sbin
    pathmunge /usr/sbin
    pathmunge /usr/local/sbin
else
    pathmunge /usr/local/sbin after
    pathmunge /usr/sbin after
    pathmunge /sbin after
fi

HOSTNAME=`/bin/hostname 2>/dev/null`
HISTSIZE=1000
if [ "$HISTCONTROL" = "ignorespace" ] ; then
    export HISTCONTROL=ignoreboth
else
    export HISTCONTROL=ignoredups
fi

export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL

for i in /etc/profile.d/*.sh ; do
    if [ -r "$i" ]; then
        if [ "$PS1" ]; then
            . $i
        else
            . $i >/dev/null 2>&1
        fi
    fi
done

unset i
unset pathmunge
5

Please don't bump posts.

With a text editor like nano or vim. You'll need to su - into root to get sufficient privileges to edit it. But, reading this file:

# System wide environment and startup programs, for login setup
# Functions and aliases go in /etc/bashrc

# It's NOT good idea to change this file unless you know what you
# are doing. Much better way is to create custom.sh shell script in
# /etc/profile.d/ to make custom changes to environment. This will
# prevent need for merging in future updates.

...and this code:

for i in /etc/profile.d/*.sh ; do
    if [ -r "$i" ]; then
        if [ "$PS1" ]; then
            . $i
        else
            . $i >/dev/null 2>&1
        fi
    fi
done

...would suggest that you create a file under /etc/profile.d/ instead.

Try creating a /etc/profile.d/99-hello.sh file with this:

#!/bin/sh

echo "Hello, ${USER}"

and see if it works when you login. It should.