Does a noninteractive login shell execute `~/.profile` or a file whose name is `$BASH_ENV`?

Question

From Bash Manual

Invoked as an interactive login shell, or with --login

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.

When an interactive login shell exits, or a non-interactive login shell executes the exit builtin command, Bash reads and executes commands from the file ~/.bash_logout, if it exists.

Invoked as an interactive non-login shell

...

Invoked non-interactively

When Bash is started non-interactively, to run a shell script, for example, it looks for the variable BASH_ENV in the environment, expands its value if it appears there, and uses the expanded value as the name of a file to read and execute. Bash behaves as if the following command were executed:

if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi

but the value of the PATH variable is not used to search for the filename.

As noted above, if a non-interactive shell is invoked with the --login option, Bash attempts to read and execute commands from the login shell startup files.

Which case does a noninteractive login shell belong to, the first case, or the third case?

The first case "Invoked as an interactive login shell, or with --login" contains the scenario of "non-interactive shell with the --login option", so I deduce that

• the first case is for login shells regardless of being interactive or noninteractive, and

• the third case is for noninteractive nonlogin shells.

Am I correct?

Thanks.

Answer 1

No, you’re not correct. Bash behaves as documented:

• the first section applies to interactive login shells, and to non-interactive shells started with the --login flag;
• the third section applies to non-interactive shells, including non-interactive login shells not started with the --login flag.

A shell can be a login shell without the --login flag. If you look at /proc/$$/cmdline from a Bash shell started by SSH on a Linux system, you’ll see it was started as -bash — the leading hyphen is the usual way of starting a login shell, and isn’t covered by the first section if it ends up being non-interactive. However if one wanted a non-interactive login shell for whatever reason, one would typically use --login to get it.