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(bashref.info)Bash Startup Files

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Bash Startup Files
==================

   This section describs how Bash executes its startup files.  If any
of the files exist but cannot be read, Bash reports an error.  Tildes
are expanded in file names as described above under Tilde Expansion
(Note: Tilde Expansion).

   Interactive shells are described in Note: Interactive Shells.

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 a login shell exits, Bash reads and executes commands from the
file `~/.bash_logout', if it exists.

Invoked as an interactive non-login shell
.........................................

   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
.........................

   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 file
name.

   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
..............................

   Bash attempts to determine when it is being run by the remote shell
daemon, usually `rshd'.  If Bash determines it is being run by rshd, 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 `rshd' does not
generally invoke the shell with those options or allow them to be
specified.

Invoked with unequal effective and real UID/GIDs
................................................

   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' variable, if it appears in the
environment, is 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.