bash 在我的 shell 程序中获取一个 C 程序的返回码
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Get the return code of a C program in my shell program
提问by molecule
Suppose I have a C program named Foo.cwhich is printing few things and returning a value named rcwhich I am executing in my shell program as follows :
假设我有一个 C 程序Foo.c，它正在打印一些东西并返回一个rc我在 shell 程序中执行的值，如下所示：
foobar=$(Foo | tail -1)
foobar=$(Foo | tail -1)
Now, the variable foobar has the last printed value of the program Foo. But without disturbing this, I want to get the return code rcof the program in my shell program.
现在，变量 foobar 具有程序的最后打印值Foo。但是在不打扰这个的情况下，我想rc在我的shell程序中获取程序的返回码。
采纳答案by Pratik Shinde
You can use "set -o pipefail" option.
您可以使用“set -o pipefail”选项。
[root@myserver Test]# set -o pipefail
[root@myserver Test]# ./a.out | tail -l
[root@myserver Test]# echo $?
100
Here my program a.out returns 100.
这里我的程序 a.out 返回 100。
Or another options is to use pipestatus environment variable. You can read about it here. http://www.linuxnix.com/2011/03/pipestatus-internal-variable.html
或者另一种选择是使用 pipestatus 环境变量。你可以在这里读到它。 http://www.linuxnix.com/2011/03/pipestatus-internal-variable.html
回答by sat
If you are using bashshell, you can use PIPESTATUSarray variable to get the status of the pipeprocess.
如果您使用的是bashshell，则可以使用PIPESTATUS数组变量来获取pipe进程的状态。
$ tail sat | wc -l
tail: cannot open ‘sat' for reading: No such file or directory
0
$ echo "${PIPESTATUS[0]} ${PIPESTATUS[1]}"
1 0
$
From man bash:
来自man bash：
PIPESTATUS
An array variable containing a list of exit status values from the processes in the most-recently-executed foreground pipeline (which may contain only a single command).
管道状态
一个数组变量，包含来自最近执行的前台管道（可能只包含一个命令）中的进程的退出状态值列表。
回答by John1024
This assigns the last line of the output of Footo foobarand Foo's exit code is assigned to code:
这将输出的最后一行分配给Footofoobar并将 Foo 的退出代码分配给code：
{ read -r foobar; read code; } < <( (Foo; echo $? ) | tail -2)
The <(...)construct is called process substitution. In the code above, the readcommands receive their stdin from the process substitution. Because of the tail -2, the process substitution produces a total of two lines. The first line is the last line produced by Fooand it is assigned to foobar. The second is assigned to code.
该<(...)构造称为进程替换。在上面的代码中，read命令从进程替换中接收它们的标准输入。由于tail -2，过程替换总共产生两行。第一行是由 生成的最后一行，Foo并将其分配给foobar。第二个分配给code.
The space between the first and second <is essential.
第一个和第二个之间的空间<是必不可少的。
Example
例子
After creating a function Foo, the above can be tested:
创建一个函数Foo后，可以测试上面的内容：
$ Foo() { echo "Testing"; false; }
$ { read -r foobar; read code; } < <( (echo "Testing"; false; echo $? ) | tail -2)
$ echo "foobar=$foobar code=$code"
foobar=Testing code=1
And:
和：
$ Foo() { echo "2nd Test"; true; }
$ { read -r foobar; read code; } < <( (Foo; echo $? ) | tail -2)
$ echo "foobar=$foobar code=$code"
foobar=2nd Test code=0
回答by rkachach
I'm afraid that you have to use a temporal file to store the output of the Foo program, get the return code and then perform the tail -1. Just like the following:
恐怕你得用一个临时文件来存储Foo程序的输出，得到返回码，然后执行tail -1。就像下面这样：
Foo > /tmp/temp_file
ret=$?
foobar=$(tail -1 /tmp/temp_file)
回答by user3156262
$?gives the return value of the last executed command.
$?给出最后执行的命令的返回值。
