“源”有什么作用？

Question

$ whatis source
source: nothing appropriate.
$ man source
No manual entry for source
$ source
bash: source: filename argument required
source: usage: source filename [arguments]

它存在，并且可以运行。为什么 Ubuntu 中没有关于它的任何文档？它有什么作用？如何安装有关它的文档？

Answer 1

source是一个 bash shell 内置命令，它在当前 shell中执行作为参数传递的文件的内容。它在.（句号）中有一个同义词。

句法

. filename [arguments]

source filename [arguments]

Answer 2

当心！./并且source都不太一样。

• ./script将脚本作为可执行文件运行，启动一个新的 shell来运行它
• source script从当前 shell环境中的filename 读取并执行命令

注意：./script不是. script，而是. script==source script

https://askubuntu.com/questions/182012/is-there-a-difference-between-and-source-in-bash-after-all?lq=1

Answer 3

了解“type”命令很有用：

> type source
source is a shell builtin

每当某些东西是内置的 shell 时，就该做man bash。

Answer 4

. (a period) 是一个bash shell 内置命令，它在当前 shell 中从作为参数传递的文件中执行命令。“来源”是“.”的同义词。

从 Bash 手册页：

. filename [arguments]
source filename [arguments]
       Read  and  execute  commands  from filename in the current shell
       environment and return the exit status of the last command  exe?
       cuted from filename.  If filename does not contain a slash, file
       names in PATH are used to find the  directory  containing  file?
       name.   The  file  searched  for in PATH need not be executable.
       When bash is  not  in  posix  mode,  the  current  directory  is
       searched  if no file is found in PATH.  If the sourcepath option
       to the shopt builtin command is turned  off,  the  PATH  is  not
       searched.   If any arguments are supplied, they become the posi?
       tional parameters when  filename  is  executed.   Otherwise  the
       positional  parameters  are unchanged.  The return status is the
       status of the last command exited within the  script  (0  if  no
       commands  are  executed),  and false if filename is not found or
       cannot be read.

Answer 5

'source' 是 '.' 的长版本。命令。在 bash 提示符下，可以执行以下操作：

source ~/.bashrc

为当前正在运行的 bash 重新加载您的（已更改？）bash 设置。

简短版本将是：

. ~/.bashrc

手册页：

. filename [arguments]
source filename [arguments]
    Read and execute commands from filename in the current shell environment and
    return the exit status of the last command executed from filename. If 
    filename does not contain a slash, file names in PATH are used to find the
    directory containing filename. The file searched for in PATH need not be
    executable. When bash is not in posix mode, the current directory is
    searched if no file is found in PATH. If the sourcepath option to the shopt
    builtin command is turned off, the PATH is not searched. If any arguments
    are supplied, they become the positional parameters when filename is
    executed. Otherwise the positional parameters are unchanged. The return 
    status is the status of the last command exited within the script (0 if no
    commands are executed), and false if filename is not found or cannot be
    read. 

Answer 6

sourcecommand在当前shell 环境中执行提供的脚本（可执行权限不是强制性的），而在新的shell 中执行提供的可执行脚本。./

source命令确实有一个同义词. filename。

为了更清楚，请查看以下设置别名的脚本。

别名

#! /bin/bash

alias myproject='cd ~/Documents/Projects/2015/NewProject'

现在我们有两个选择来执行这个脚本。但是只有一个选项，可以在这两个选项中创建当前 shell 所需的别名。

选项1： ./make_alias

首先使脚本可执行。

chmod +x make_alias

执行

./make_alias

核实

alias

输出

**nothing**

哎呀！别名随新外壳一起消失了。

让我们选择第二个选项。

选项 2： source make_alias

执行

source make_alias

或者

. make_alias

核实

alias

输出

alias myproject='cd ~/Documents/Projects/2015/NewProject'

是的，别名已设置。

Answer 7

如有疑问，最好的办法是使用以下info命令：

[root@abc ~]# info source

BASH BUILTIN COMMANDS
       Unless otherwise noted, each builtin command documented in this section
       as accepting options preceded by - accepts -- to signify the end of the
       options.   The  :, true, false, and test builtins do not accept options
       and do not treat -- specially.  The exit, logout, break, continue, let,
       and  shift builtins accept and process arguments beginning with - with-
       out requiring --.  Other builtins that accept  arguments  but  are  not
       specified  as accepting options interpret arguments beginning with - as
       invalid options and require -- to prevent this interpretation.
       : [arguments]
              No effect; the command does nothing beyond  expanding  arguments
              and  performing any specified redirections.  A zero exit code is
              returned.

        .  filename [arguments]
       source filename [arguments]
              Read and execute commands from filename  in  the  current  shell
              environment  and return the exit status of the last command exe-
              cuted from filename.  If filename does not contain a slash, file
              names  in  PATH  are used to find the directory containing file-
              name.  The file searched for in PATH  need  not  be  executable.
              When  bash  is  not  in  posix  mode,  the  current directory is
              searched if no file is found in PATH.  If the sourcepath  option
              to  the  shopt  builtin  command  is turned off, the PATH is not
              searched.  If any arguments are supplied, they become the  posi-
              tional  parameters  when  filename  is  executed.  Otherwise the
              positional parameters are unchanged.  The return status  is  the
              status  of  the  last  command exited within the script (0 if no
              commands are executed), and false if filename is  not  found  or
              cannot be read.

Answer 8

来自 Linux 文档项目，高级 Bash 脚本指南，
第 15 章 -内部命令和内置：

来源，。（点命令）：
当从命令行调用此命令时，将执行脚本。在脚本中，源文件名加载文件文件名。获取文件（点命令）将代码导入脚本，附加到脚本（与 C 程序中的 #include 指令效果相同）。最终结果与“来源”代码行实际存在于脚本主体中一样。这在多个脚本使用公共数据文件或函数库的情况下很有用。
如果源文件本身是一个可执行脚本，那么它将运行，然后将控制权返回给调用它的脚本。为此，源可执行脚本可能会使用返回值。

因此，对于那些熟悉 C 编程语言的人来说，获取文件的效果类似于#include指令。

另请注意，您可以将位置参数传递给正在获取的文件，例如：

$ source $filename $arg1 arg2

Answer 9

在 shell 中键入命令“help source”。

你会得到这样的输出：

source: source filename [arguments]

Execute commands from a file in the current shell.

Read and execute commands from FILENAME in the current shell.  The
entries in $PATH are used to find the directory containing FILENAME.
If any ARGUMENTS are supplied, they become the positional parameters
when FILENAME is executed.

Exit Status:
Returns the status of the last command executed in FILENAME; fails if
FILENAME cannot be read.

Answer 10

应该指出的是，尽管这是一个很棒的命令，但source它及其简写都.不会来源 多个文件，这意味着

source *.sh

或者

. script1.sh script2.sh

不管用。

我们可以使用循环回退for，但它会多次发出可执行文件，创建多个命令或发出多个命令。

结论：source不接受多个文件作为输入。参数必须是一个。

恕我直言，这很糟糕。