使用 linux 如何将文件的内容作为参数传递给可执行文件？
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using linux how can I pass the contents of a file as a parameter to an executable?
提问by al b.
let's say I want to run ./programwith a string argument
假设我想./program使用字符串参数运行
instead of typing
./program stringeach time, how can I do ./program <file>where <file>is a file that contains string?
而不是键入
./program string每一次，我该怎么办./program <file>，其中<file>是包含的字符串的文件？
thankyou
谢谢你
采纳答案by robbrit
This should do the trick:
这应该可以解决问题：
./program `cat file`
If you want the entire file content in a single argument, add double quotation (tested in bash. I think It may vary shell to shell) :
如果您希望在单个参数中包含整个文件内容，请添加双引号（在 bash 中测试。我认为它可能因外壳而异）：
./program "`cat file`"
回答by John Kugelman
Command
命令
./program "$(< file)"
Explanation
解释
$(cmd)runs a command and converts its output into a string.$(cmd)can also be written with backticks as`cmd`. I prefer the newer$(cmd)as it nests better than the old school backticks.The command we want is
cat file. And then from the bash man page:The command substitution
$(cat file)can be replaced by the equivalent but faster$(< file).The quotes around it make sure that whitespace is preserved, just in case you have spaces or newlines inside of your file. Properly quoting things in shell scripts is a skill that is sorely lacking. Quoting variables and command substitutions is a good habit to good into so you don't get bit later when your file names or variable values have spaces or control characters or other weirdnesses.
$(cmd)运行命令并将其输出转换为字符串。$(cmd)也可以用反引号写成`cmd`. 我更喜欢新的，$(cmd)因为它比旧学校的反引号更好地嵌套。我们想要的命令是
cat file. 然后从 bash 手册页：命令替换
$(cat file)可以替换为等效但更快的$(< file)。它周围的引号确保保留空格，以防万一您的文件中有空格或换行符。在 shell 脚本中正确引用内容是一项非常缺乏的技能。引用变量和命令替换是一个很好的习惯，所以当你的文件名或变量值有空格或控制字符或其他奇怪的东西时，你不会迟到。
回答by paxdiablo
You can use one of:
您可以使用以下之一：
./program $(cat file)
./program "$(cat file)"
The latter is useful if there may be multiple words in the file and you want them to be treated as a single argument. In any case, I prefer the use if $()to backticks simply due to it's ability to nest (which is probably not a requirementin this case).
如果文件中可能有多个单词并且您希望将它们视为单个参数，则后者很有用。在任何情况下，我更喜欢使用，如果$()以反引号只是由于它的能力巢（这可能不是一个要求，在这种情况下）。
Also keep in mind that this answer (and others) are more related to the shell in use rather than Linux itself. Since the predominant and the best :-)shell seems to be bash, I've coded specifically for that.
还要记住，这个答案（和其他答案）与使用的 shell 更相关，而不是 Linux 本身。由于主要和最好的 :-)shell 似乎是bash，我专门为此编写了代码。
This is actually a fairly common way of killing processes under UNIX lookalikes. A daemon (like cron) will write its process ID to a file (like /var/cron.pid) and you can signal it with something like:
这实际上是在 UNIX 相似程序下杀死进程的一种相当常见的方法。守护进程（如cron）会将其进程 ID 写入文件（如/var/cron.pid），您可以使用以下内容向其发送信号：
kill -HUP $(cat /var/cron.pid)
回答by Matthew
Another option is xargs:
另一种选择是 xargs：
cat file | xargs ./program
I personally find this version easier to read, especially if you're doing more than just catting a file.
我个人觉得这个版本更容易阅读，尤其是当你做的不仅仅是文件分类时。
From the man page:
从手册页：
xargs reads items from the standard input, delimited by blanks or newlines, and executes the command one or more times with any initial-arguments followed by items read from standard input.
xargs 从标准输入读取项目，以空格或换行符分隔，并使用任何初始参数执行命令一次或多次，后跟从标准输入读取的项目。
In plain speak, xargs will execute ./program on each line/word that is being piped to it.
简单地说， xargs 将在通过管道传输到它的每一行/单词上执行 ./program 。
See man xargs for more options.
有关更多选项，请参阅 man xargs。
回答by Jon Deaton
All the above answers work but I find the cleanest and easiest to type option is
以上所有答案都有效，但我发现最干净、最容易输入的选项是
xargs < file ./program
回答by Habeeb Perwad
This is extension to @robbrit answer.
这是@robbrit 答案的扩展。
Consider a file.txtwith content:
考虑一个包含内容的file.txt：
1 2 3
4 5 6
And the a program.cwith content:
还有一个包含内容的program.c：
#include<stdio.h>
void main(int argc, char** argv)
{
for (int i = 0; i < argc; i++)
printf("Arg %d: %s\n", i, argv[i]);
}
Here is what happen if you pass command line arguments with quotes and without:
如果您传递带引号和不带引号的命令行参数，会发生以下情况：
$ gcc program.c -o program
$ ./program `cat file`
Arg 0: ./program
Arg 1: 1
Arg 2: 2
Arg 3: 3
Arg 4: 4
Arg 5: 5
Arg 6: 6
$ ./program "`cat file`"
Arg 0: ./program
Arg 1: 1 2 3
4 5 6
