How to Start a Shell Without Any User Configuration

How to start a shell without any user configuration?

You can pass the --noprofile and --norc command-line options:

$ bash --noprofile --norc

You will find documentation about these options in the man page.

How do I run a shell script without using sh or bash commands?

Add a "shebang" at the top of your file:

#!/bin/bash

And make your file executable (chmod +x script.sh).

Finally, modify your path to add the directory where your script is located:

export PATH=$PATH:/appropriate/directory

(typically, you want $HOME/bin for storing your own scripts)

Execute a bash script the first time shell opens

Bash has two files, from the user perspective, that perform "setup" when it is launched:

• .bash_profile - This file is executed whenever you open an interactive login shell. This file may also be named .profile in certain distributions or configurations. .profile is usually used for non-Bash specific configuration items. Also be aware that if you have the little used .bash_login, .bash_profile will prevent that file from being used, though it is otherwise equivalent. .bash_profile is standard.
• .bashrc - This file is executed for all other bash instances. Note that it is common for people to call .bashrc from .bash_profile to create consistency.

A login shell is spawned when you login; via ssh, telnet, at a console, etc. You can also force the launch of a login shell (forcing .bash_profile) to be processed by starting a shell under su like so:

su - username

Here, the dash indicates that this should be processed as a login shell.

Neither of these seem to be the correct answer for your question, however, unless you are certain to login once each day and only once each day.

A better approach in your case would be to use the cron. Crontab allows you to schedule jobs to run at any desired interval. For daily execution, you would likely want a line configured like so:

0 5 * * *              /home/user/script

This would cause the user's script to execute at 5am every day. The columns are:

0 5 * * *
^ ^ ^ ^ ^------ Day of week
^ ^ ^ ^-------- Month of year
^ ^ ^---------- Day of month
^ ^------------ Hour of day
^-------------- Minute of hour

Each of those fields can also represent a comma separated list or even an arithmetic expression. For example, the following will execute the script four times during the 5 AM hour:

*/4 5 * * *

Terminal: Where is the shell start-up file?

You're probably using bash so just add these 3 lines to ~/.bash_profile:

$ cat >> ~/.bash_profile
export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/directory-you-do-development-in
source /usr/local/bin/virtualenvwrapper.sh
^D

where ^D means you type Control+D (EOF).

Then either close your terminal window and open a new one, or you can "reload" your .bash_profile like this:

$ source ~/.bash_profile

Changing default shell in Linux

Try linux command chsh.

The detailed command is chsh -s /bin/bash.
It will prompt you to enter your password.
Your default login shell is /bin/bash now. You must log out and log back in to see this change.

The following is quoted from man page:

The chsh command changes the user login shell. This determines the
name
of the users initial login command. A normal user may only change the
login shell for her own account, the superuser may change the login
shell for any account

This command will change the default login shell permanently.

Note: If your user account is remote such as on Kerberos authentication (e.g. Enterprise RHEL) then you will not be able to use chsh.

Shell Script (not bash) : How to redirect script into su root?

If you are just asking how to do a herestring when the shell you are using does not support herestrings, then:

su root -c '/some/foo/command' << EOF
somepass
EOF

I can't write this response without at least remarking that passing a password this way is not secure.

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