bash: Bash Startup Files
6.2 Bash Startup Files
======================
This section describes how Bash executes its startup files. If any of
the files exist but cannot be read, Bash reports an error. Tildes are
expanded in filenames as described above under Tilde Expansion (
Tilde Expansion).
Interactive shells are described in Interactive Shells.
Invoked as an interactive login shell, or with '--login'
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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
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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'.
So, typically, your '~/.bash_profile' contains the line
if [ -f ~/.bashrc ]; then . ~/.bashrc; fi
after (or before) any login-specific initializations.
Invoked non-interactively
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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.
Invoked with name 'sh'
......................
If Bash is invoked with the name 'sh', it tries to mimic the startup
behavior of historical versions of 'sh' as closely as possible, while
conforming to the POSIX standard as well.
When invoked as an interactive login shell, or as a non-interactive
shell with the '--login' option, it first attempts to read and execute
commands from '/etc/profile' and '~/.profile', in that order. The
'--noprofile' option may be used to inhibit this behavior. When invoked
as an interactive shell with the name 'sh', Bash looks for the variable
'ENV', expands its value if it is defined, and uses the expanded value
as the name of a file to read and execute. Since a shell invoked as
'sh' does not attempt to read and execute commands from any other
startup files, the '--rcfile' option has no effect. A non-interactive
shell invoked with the name 'sh' does not attempt to read any other
startup files.
When invoked as 'sh', Bash enters POSIX mode after the startup files
are read.
Invoked in POSIX mode
.....................
When Bash is started in POSIX mode, as with the '--posix' command line
option, it follows the POSIX standard for startup files. In this mode,
interactive shells expand the 'ENV' variable and commands are read and
executed from the file whose name is the expanded value. No other
startup files are read.
Invoked by remote shell daemon
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Bash attempts to determine when it is being run with its standard input
connected to a network connection, as when executed by the remote shell
daemon, usually 'rshd', or the secure shell daemon 'sshd'. If Bash
determines it is being run in this fashion, it reads and executes
commands from '~/.bashrc', if that file exists and is readable. It will
not do this if invoked as 'sh'. The '--norc' option may be used to
inhibit this behavior, and the '--rcfile' option may be used to force
another file to be read, but neither 'rshd' nor 'sshd' generally invoke
the shell with those options or allow them to be specified.
Invoked with unequal effective and real UID/GIDs
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If Bash is started with the effective user (group) id not equal to the
real user (group) id, and the '-p' option is not supplied, no startup
files are read, shell functions are not inherited from the environment,
the 'SHELLOPTS', 'BASHOPTS', 'CDPATH', and 'GLOBIGNORE' variables, if
they appear in the environment, are ignored, and the effective user id
is set to the real user id. If the '-p' option is supplied at
invocation, the startup behavior is the same, but the effective user id
is not reset.
Info Catalog
bash: Invoking Bash
bash: Bash Features
bash: Interactive Shells