“./"之间的区别和“sh"在 UNIX 中 [英] Difference between "./" and "sh" in UNIX

问题描述

有时我看到很少有脚本是通过sh"命令执行的，有时是通过./"命令执行的.我无法理解它们之间的确切区别.请帮帮我.

Sometimes i see that few scripts are executed through "sh" command and sometimes through "./" command.I am not able to understand the exact difference between them.Please help me out .

推荐答案

sh file 在新的 shell 进程中执行 shell-script 文件.

sh file executes a shell-script file in a new shell process.

<代码>.file 在当前 shell 进程中执行一个 shell-script 文件.

. file executes a shell-script file in the current shell process.

./file 将执行当前目录中的文件.该文件可以是二进制可执行文件，也可以以 hashbang 行开头(文件的第一行格式为 #!....，例如 #!/usr/文件中的 bin/ruby 表示脚本需要作为 Ruby 文件执行).该文件需要设置可执行标志.

./file will execute the file in the current directory. The file can be a binary executable, or it can start with a hashbang line (the first line of the file in form of #!...., for example #!/usr/bin/ruby in a file would signify the script needs to be executed as a Ruby file). The file needs to have the executable flag set.

例如，如果您有脚本 test.sh:

For example, if you have the script test.sh:

#!/bin/sh

TEST=present

并且你用 sh test.sh 执行它，你会启动一个新的 sh(或者更确切地说 bash，最有可能的，作为在现代系统中，一个与另一个软链接)，然后在其中定义一个新变量，然后退出.随后的 echo $TEST 打印一个空行 - 变量未在外壳中设置.

and you execute it with sh test.sh, you'd launch a new sh (or rather bash, most likely, as one is softlinked to the other in modern systems), then define a new variable inside it, then exit. A subsequent echo $TEST prints an empty line - the variable is not set in the outer shell.

如果您使用 启动它.test.sh，您将使用当前 shell 执行脚本.echo $TEST 的结果将打印 present.

If you launch it using . test.sh, you'd execute the script using the current shell. The result of echo $TEST would print present.

如果你使用 ./test.sh 启动它，第一行 #!/bin/sh 将被检测到，那么它就像你写的一样/bin/sh ./test.sh，在这种情况下归结为第一种情况.但是，如果 hashbang 行是，例如，#!/usr/bin/perl -w，则该文件将使用 /usr/bin/perl -w ./test 执行.sh.

If you launch it using ./test.sh, the first line #!/bin/sh would be detected, then it would be exactly as if you wrote /bin/sh ./test.sh, which in this case boils down to the first scenario. But if the hashbang line was, for example, #!/usr/bin/perl -w, the file would have been executed with /usr/bin/perl -w ./test.sh.

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