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Full Discussion: Understanding the difference between individual BASH login scripts
Top Forums UNIX for Beginners Questions & Answers Understanding the difference between individual BASH login scripts Post 303006891 by Corona688 on Wednesday 8th of November 2017 05:35:36 PM
Old 11-08-2017
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.

Code:
man bash

...

FILES
...
       /etc/profile
              The systemwide initialization file, executed for login shells
       ~/.bash_profile
              The personal initialization file, executed for login shells
       ~/.bashrc
              The individual per-interactive-shell startup file
       ~/.bash_logout
              The individual login shell cleanup file, executed when  a  login
              shell exits
...

These are the files bash loads and when it loads them. Anything else is a command someone dropped into one of those files.

Quote:
I've seen people posting about how one command (like umask) would work in one script but not another and I haven't seen a clear cut definition of which scripts should contain what
Imagine this script:

Code:
#!/bin/bash

cd /etc

Set the file executable and run it with ./changedir.sh and it will create a new shell, change directory to /etc/ in that new shell, and die, leaving you in your original shell which is still wherever you left it.

If you run that script with . changedir.sh on the other hand - note the space - that instructs your own shell to load and run that code, and it will actually move your current shell.

And if you run cd /etc/ first, then run that script, the new shell will already have /etc/ as its current directory, copying it from yours.

cd, umask, and variables in general are like that. If you run it in your shell, new shells created afterewards get copies of those settings, otherwise, each process is independent.

Init scripts like /etc/profile, et cetera, all run inside your current shell anyway.
 

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LEARN ABOUT HPUX

chsh

chsh(1) 						      General Commands Manual							   chsh(1)

NAME

       chsh - change default login shell

SYNOPSIS

       login-name [shell]

       login-name [shell]

       login-name [shell]

       login-name [shell]

DESCRIPTION

       The command changes the login-shell for a user's login name in the repository (see passwd(1)).

       The  DCE  repository is only available if Integrated Login has been configured; see auth.adm(1M).  If Integrated Login has been configured,
       other considerations apply.  A user with appropriate DCE privileges is capable of modifying a user's shell;  this  is  not  dependent  upon
       superuser privileges.

       If the repository is not specified (as in [login-name]), the login shell is changed in the file only.

       Run after running to make sure the information was processed correctly.

   Notes
       The  command  is  a hard link to the command. When is executed, actually the command gets executed with appropriate arguments to change the
       user login shell in the repository specified in command line. If no repository is specified, the login shell is changed in the file.

   Arguments
	      login-name  A login name of a user.

	      shell	  The absolute path name of a shell.  If the file exists, the new login shell must be listed in that file.  Otherwise, you
			  can specify one of the standard shells listed in the getusershell(3C) manual entry.  If shell is omitted, it defaults to
			  the POSIX shell,

   Options
       The following option is recognized:

	      Specify the repository to which the operation is to be applied.
		     Supported repositories include and

   Security Restrictions
       You must have appropriate privileges to use the optional login-name argument to change another user's login shell.

NETWORKING FEATURES

   NFS
       File can be implemented as a Network Information Service (NIS) database.

EXAMPLES

       To change the login shell for user to the default:

       To change the login shell for user to the C shell:

       To change the login shell for user to the Korn shell in the DCE registry:

WARNINGS

       If two or more users try to write the file at the same time, a passwd locking mechanism was devised.  If this locking  fails  after  subse-
       quent retrying, terminates.

AUTHOR

       was developed by HP and the University of California, Berkeley.

FILES

SEE ALSO

       chfn(1), csh(1), ksh(1), passwd(1), sh(1), sh-posix(1), getusershell(3C), pam(3), passwd(4), shells(4).

																	   chsh(1)
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