In this post, I would like to share causes and solutions to a few issues related to login shell.
Default shell is not bash
When I logged in, I found that somehow my default shell (
echo $SHELL) is
/bin/sh instead of
/bin/bash. We can change the default shell with
command like this:
chsh -s /bin/bash
Make sure that the shell you want to switch are set in
you will fail.
bashrc or bash_profile not sourced after login
Another issue is that when I sshed to the server, I found that only settings
.bash_profile is sourced. Settings inside
.bashrc didn't take
effect. Before we delve into this problem, we need first to understand the
basic concept of login shell and interactive shell.
Login and interactive shell
A login shell is usually the shell when the user first log in to the
system. If the user start another shell or use
bash inside the current
shell, then the user will probably start a non-login shell1. To
check whether the bash shell is a login shell, use the following
# only works for bash shopt -q login_shell && echo 'Login shell' || echo 'Not login shell'
Roughly speaking, an interactive shell is a shell that the user can
interact with via the terminal, i.e., typing some command, sending it to
the shell and getting output. If you run a script
test.sh inside the
shell instead by using
bash test.sh. In fact, a non-interactive bash
shell is started to execute the command inside
test.sh. Now, you get a
sense of what interactive means. To check if a bash shell is
interactive, you can see if
i is present in the variable
echo $- # output may be: himBHs
According to the above statements, we now have four different types of shell:
- interactive login shell
- interactive non-login shell
- non-interactive login shell
- non-interactive non-login shell
In the following table, I show how you can get these shells:
|login||when you log into a server normally||ssh xxx@ip < test.sh|
|non-login||start a new bash shell inside the login shell||when you execute script inside the login shell|
Non-interactive login shell is extremely rare. You can start one when you run a local script via ssh on remote.:
ssh xxx@ip < test.sh
To verify that we have started a non-interactive login shell, put the
following the command inside
echo $- shopt -q login_shell && echo 'Login shell' || echo 'Not login shell'
The output of remote server will be:
hBs Login shell
.bashrc not sourced
After looking up the bash manual, the section on startup file explains this behaviour:
When Bash is invoked as an interactive login shell, or as a non-interactive shell with the –login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The –noprofile option may be used when the shell is started to inhibit this behavior.
According to the above description, when you log into the server (bash
is interactive login shell), bash will first source
it will source
the order given. The first one which exists and is readable is sourced.
~/.bashrc is sourced during the login process.
If you need to source
.bashrc during login process, you can add the
following setting to
if [ -f "$HOME/.bashrc" ]; then source $HOME/.bashrc fi
.bash_profile not sourced
Another case I met with another server is that
~/.bash_profile is not
executed during login. A little background here: for this destination
server, I need to log into a jump
server, and choose the
destination server. All users are initially log in with the same user
name. Then each user will have to switch to his/her own account via
That is problem here. The shell started by mere
su USERNAME is an
interactive non-login shell. In this case, according to the bash manual:
When an interactive shell that is not a login shell is started, Bash reads and executes commands from ~/.bashrc, if that file exists. This may be inhibited by using the –norc option. The –rcfile file option will force Bash to read and execute commands from file instead of ~/.bashrc.
It means that only settings inside
~/.bashrc is sourced. The
solution to this issue is simple: invoke
su command with
to specify that we want a login shell.
- Bashrc isn’t always run when I log in.
- Change shell in Ubuntu.
- How to get non-interactive login shell.
- How to check if a shell’s type: login or interactive.
- Difference between login, non-login, interactive and non-interactive shells.
- Zsh doc on login and interactive shells.
- Difference between bashrc and bash_profile.
That is not always true. For example, for macOS, new terminal started by Terminal.app is actually a login shell. ↩︎
License CC BY-NC-ND 4.0