bash如何處執行啟動檔案 --節選自 man bash

節選自 man  bash:      
GNU bash，版本 4.3.42(4)-release (x86_64-unknown-cygwin)

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 Expan‐
sion in the EXPANSION section。


接下來的段落描述bash如何執行它的啟動檔案。
如果任何一個檔案存在，但不能被讀取，bash報告一個錯誤。
檔名的波浪符號~會按照"擴充套件部分"的"波浪擴充套件"的描述進行擴充套件。


When bash is invoked as an interactive login shell, or as a non-inter‐
active shell with the --login option, it first reads and executes com‐
mands 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.


當bash以--login引數作為一個互動式登入shell被呼叫，或者作為一個非互動式登入shell被呼叫的時候，如果/etc/profile存在，它首先讀取和執行/etc/profile裡面的命令。讀取/etc/profile後，bash會在~/.bash_profile,~/.bash_login和~/.profile按順序尋找，找到第一個存在並且可讀的檔案，讀取並執行其中的命令。--noprofile選項用於禁止這樣的特性。




When a login shell exits, bash reads and executes commands from the
file ~/.bash_logout, if it exists.


當一個登入shell退出的時候，如果~/.bash_logout存在，bash會讀取和執行~/.bash_logout。


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.


當一個互動式的非登入shell啟動的時候，如果~/.bashrc存在，bash
會讀取和執行~/.bashrc。--norc選項會禁止這樣的特性。--rcfile選項會
強制bash用指定的檔案代替~/.bashrc讀取和執行命令。


 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  com‐
       mand 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.


     當bash以非互動式啟動，比如執行一個指令碼，它查詢環境變數BASH_ENV，
如果查詢到了，就會擴充套件BASH_ENV的值作為檔名，然後讀取和執行這個檔案。
bash的行為就像執行下面的命令:
           if [ -n "$BASH_ENV" ];then . "$BASH_ENV";fi
但是搜尋檔名的時候，不會使用PATH變數的值。

      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 exe‐
       cute commands from /etc/profile and ~/.profile, in that order.  The --noprofile option may be used to inhibit this behavior.  When invoked as  an  interac‐
       tive 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 rshd does not 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.