Understanding the difference between individual BASH login scripts Post: 303006893

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Top Forums UNIX for Beginners Questions & Answers Understanding the difference between individual BASH login scripts Post 303006893 by bodisha on Wednesday 8th of November 2017 06:18:58 PM

11-08-2017

Registered User

Quote:

Originally Posted by Corona688

First off, these files are shell scripts, so they do whatever their author wanted. This is responsible for a lot of the confusion - /etc/bashrc is not a file bash will load unless something else tells it to, but someone could easily have put . /etc/bashrc into /etc/profile for the same effect. You have to read these profile scripts to see what they do, no other way to know.

Thanks for the quick reply! I'm still unclear on a few points and I hope you don't mind a follow up question to straighten me out

To address your first comment about "they do whatever their author wanted"... When inspecting the files in question I noticed the comment "Functions and aliases go in /etc/bashrc" in the /etc/profile file

Based on some of the posts I've read while researching the subject... I got the impression certain files had very specific purposes... And I've even seen posts were people were saying builtin commands (like umask) wouldn't work in certain files... Can you confirm this? If so I'm trying to understand the exact rules surrounding which sort of functionality the individual startup files can support

The second part of your comment I'd like to address is you said

"/etc/bashrc is not a file bash will load unless something else tells it to, but someone could easily have put /etc/bashrc into /etc/profile"

While trying to understand this topic I edited each file and put echo commands in the individual files to see when they'd start. The /etc/bashrc started in both login and non-login shells. It loaded after the /etc/profile in a login shell (putty) and in the non-login shell (The gnome GUI terminal) when the /etc/profile didn't run.

I looked through the profile and all the scripts under the /etc/profile.d directory and couldn't locate anything calling the /etc/bashrc script. Could I ask you for a clue on where else I might look to see what's starting it?

Thanks for your patience

bodisha

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LEARN ABOUT X11R4

chsh

CHSH(1)                                                            User Commands                                                           CHSH(1)

NAME

       chsh - change login shell

SYNOPSIS

       chsh [options] [LOGIN]

DESCRIPTION

       The chsh command changes the user login shell. This determines the name of the user's 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.

OPTIONS

       The options which apply to the chsh command are:

       -h, --help
           Display help message and exit.

       -R, --root CHROOT_DIR
           Apply changes in the CHROOT_DIR directory and use the configuration files from the CHROOT_DIR directory.

       -s, --shell SHELL
           The name of the user's new login shell. Setting this field to blank causes the system to select the default login shell.

       If the -s option is not selected, chsh operates in an interactive fashion, prompting the user with the current login shell. Enter the new
       value to change the shell, or leave the line blank to use the current one. The current shell is displayed between a pair of [ ] marks.

NOTE

       The only restriction placed on the login shell is that the command name must be listed in /etc/shells, unless the invoker is the superuser,
       and then any value may be added. An account with a restricted login shell may not change her login shell. For this reason, placing /bin/rsh
       in /etc/shells is discouraged since accidentally changing to a restricted shell would prevent the user from ever changing her login shell
       back to its original value.

FILES

       /etc/passwd
           User account information.

       /etc/shells
           List of valid login shells.

       /etc/login.defs
           Shadow password suite configuration.

SEE ALSO

       chfn(1), login.defs(5), passwd(5).

shadow-utils 4.5                                                    01/25/2018                                                             CHSH(1)

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