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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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RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a file name containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)
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