gNU Bourne-Again SHell (GNU Bourne-Again SHell)
Вызов (Invocation)
A login shell is one whose first character of argument zero is a
-, or one started with the --login option.
An interactive shell is one started without non-option arguments
(unless -s is specified) and without the -c option whose standard
input and error are both connected to terminals (as determined by
isatty(3)), or one started with the -i option. PS1 is set and $-
includes i if bash is interactive, allowing a shell script or a
startup file to test this state.
The following paragraphs describe how bash executes its startup
files. If any of the files exist but cannot be read, bash
reports an error. Tildes are expanded in filenames as described
below under Tilde Expansion in the EXPANSION section.
When bash is invoked as an interactive login shell, or as a non-
interactive shell with the --login option, it first reads and
executes commands from the file /etc/profile, if that file
exists. After reading that file, it looks for ~/.bash_profile,
~/.bash_login, and ~/.profile, in that order, and reads and
executes commands from the first one that exists and is readable.
The --noprofile option may be used when the shell is started to
inhibit this behavior.
When an interactive login shell exits, or a non-interactive login
shell executes the exit builtin command, bash reads and executes
commands from the file ~/.bash_logout, if it exists.
When an interactive shell that is not a login shell is started,
bash reads and executes commands from ~/.bashrc, if that file
exists. This may be inhibited by using the --norc option. The
--rcfile file option will force bash to read and execute commands
from file instead of ~/.bashrc.
When bash is started non-interactively, to run a shell script,
for example, it looks for the variable BASH_ENV in the
environment, expands its value if it appears there, and uses the
expanded value as the name of a file to read and execute. Bash
behaves as if the following command were executed:
if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi
but the value of the PATH variable is not used to search for the
filename.
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 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
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.
If the shell 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.
