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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 (see Tilde Expansion).
Interactive shells are described in Interactive Shells.
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.
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.
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.
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.
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.
Bash attempts to determine when it is being run with its standard input
connected to a network connection, as when executed by
the historical remote shell daemon, usually rshd
,
or the secure shell daemon sshd
.
If Bash
determines it is being run non-interactively 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.
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.
Next: Interactive Shells, Previous: Invoking Bash, Up: Bash Features [Contents][Index]