BASH 脚本 - 使用变量执行命令并存储结果
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BASH script - execute command with variable and store result
提问by designerrr
I don't know how execute a command with variable and get result of this.
I have many .hand .cfiles and I need convert each from ISO-8859 to UTF-8.
我不知道如何使用变量执行命令并获得结果。我有很多.h和.c文件，我需要将每个从ISO-8859为UTF-8。
So I make:
所以我做：
ls | grep "\.[ch]" | xargs myscript.sh
And in my script in variable $1is the filename. Now I need to perform
在我的脚本中，变量$1是文件名。现在我需要执行
iconv -f ISO-8859 -t UTF-8
and store result of this, because iconvprint to stdout.
并存储结果，因为iconv打印到标准输出。
result=`iconv -f ISO-8859 -t UTF-8 `
echo $result
This seems to be not working, because it give me some mismatch instead of converted $1.
这似乎不起作用，因为它给了我一些不匹配而不是转换的$1.
采纳答案by Michael
If you need to do some kind of transformation on the data first, you can "capture" output with the following syntax:
如果您需要先对数据进行某种转换，您可以使用以下语法“捕获”输出：
result="$(iconv -f ISO-8859 -t UTF-8 )"
There is a gotcha here as well: if you are going to be storing large amounts of data with potential whitespace or other meddlesome characters in it, be sure to always quote the variable ("$result"instead of $result) to ensure it gets treated as a single string.
这里也有一个问题：如果您要存储大量带有潜在空格或其他麻烦字符的数据，请务必始终引用变量（"$result"而不是$result）以确保将其视为单个字符串。
回答by Jo So
Here is a solution that even handles newlines:
这是一个甚至可以处理换行符的解决方案：
find -name '*.[ch]' \
-exec mv '{}' '{}.backup' \; \
-exec iconv -f ISO-8859 -t UTF-8 '{}.backup' -o '{}' \;
Generally, NEVER parse filenames if you are going to use the results. The only sane ways I know of are
通常，如果要使用结果，请永远不要解析文件名。我所知道的唯一理智的方法是
- Use shell globs, e.g.
for file in ./*.[ch] ; do echo "$file" ; done. Only works for one directory. - Use find in combination with -exec
- Use find in combination with -print0 (which prints the filenames as \0-separated strings) and use the output to build commandlines with
xargs -0and probably a helper script. This is quite cumbersome, though.
- 使用 shell glob，例如
for file in ./*.[ch] ; do echo "$file" ; done. 仅适用于一个目录。 - 将 find 与 -exec 结合使用
- 将 find 与 -print0 结合使用（将文件名打印为以 \0 分隔的字符串）并使用输出来构建命令行，
xargs -0并且可能是一个帮助脚本。不过，这相当麻烦。
Also, make sure that relative filenames you use are prefixed with ./. Calling mv -from -toisn't safe, but mv ./-from ./-tois, and does what you want. E.g. when globbing, go with ./*.crather than *.c.
此外，请确保您使用的相关文件名以./. 打电话mv -from -to不安全，但mv ./-from ./-to可以，而且可以做你想做的事。例如，在通配时，使用 with./*.c而不是*.c。
回答by sehe
I'd do as such:
我会这样做：
while read filename;
do
mv "$filename" "$filename.bck" && \
iconv -f ISO-8859 -t UTF-8 "$filename.bck" > "$filename"
done < find -iname '*.[hc]'
This creates backups on the fly and also handles files with whitespace (not newline characters).
这会动态创建备份并处理带有空格（不是换行符）的文件。
