bash 写入文件，但如果存在则覆盖它
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Write to file, but overwrite it if it exists
提问by switz
echo "text" >> 'Users/Name/Desktop/TheAccount.txt'
How do I make it so it creates the file if it doesn't exist, but overwrites it if it already exists. Right now this script just appends.
我如何制作它以便它在文件不存在时创建它，但如果它已经存在则覆盖它。现在这个脚本只是附加。
回答by Nylon Smile
A little understanding of how *nix pipes work would help.
稍微了解 *nix 管道的工作原理会有所帮助。
In short the >>redirection operator will append lines to the end of the specified file, where-as the single greater than >will empty and overwrite the file.
简而言之，>>重定向操作符会将行附加到指定文件的末尾，其中单个大于>将清空并覆盖文件。
echo "text" > 'Users/Name/Desktop/TheAccount.txt'
回答by BrDaHa
In Bash, if you have set noclobber a la set -o noclobber, then you use the syntax >|
在 Bash 中，如果您设置了 noclobber a la set -o noclobber，则使用语法>|
For example:
例如：
echo "some text" >| existing_file
echo "some text" >| existing_file
This also works if the file doesn't exist yet
如果文件尚不存在，这也有效
回答by Alex Gray
Despite NylonSmile's answer, which is "sort of" correct.. I was unable to overwritefiles, in this manner..
尽管NylonSmile's answer，这是“有点”正确..我无法以这种方式覆盖文件..
echo "i know about Pipes, girlfriend" > thatAnswer
echo "i know about Pipes, girlfriend" > thatAnswer
zsh: file exists: thatAnswer
zsh: file exists: thatAnswer
to solve my issues.. I had to use... >!, á la..
解决我的问题.. 我不得不使用... >!, á la..
[[ $FORCE_IT == 'YES' ]] && echo "$@" >! "$X" || echo "$@" > "$X"
Obviously, be careful with this...
显然，要小心这个......
回答by computerist
If your environment doesn't allow overwriting with >, use pipe |and teeinstead as follows:
如果您的环境不允许的方式覆盖>，使用管道|和tee替代如下：
echo "text" | tee 'Users/Name/Desktop/TheAccount.txt'
Note this will also print to the stdout. In case this is unwanted, you can redirect the output to /dev/nullas follows:
请注意，这也将打印到标准输出。如果这是不需要的，您可以将输出重定向到/dev/null如下：
echo "text" | tee 'Users/Name/Desktop/TheAccount.txt' > /dev/null
回答by Balaji Boggaram Ramanarayan
#!/bin/bash
cat <<EOF > SampleFile
Put Some text here
Put some text here
Put some text here
EOF
回答by greensaxman
Just noting that if you wish to redirect both std::cerr and std::cout to a file while you have noclobber set (i.e. set -o noclobber), you can use the code:
请注意，如果您希望在设置 noclobber 时将 std::cerr 和 std::cout 重定向到文件（即set -o noclobber），则可以使用以下代码：
cmd >|file.txt 2>&1
More information about this can be seen at https://stackoverflow.com/a/876242.
有关这方面的更多信息，请访问https://stackoverflow.com/a/876242。
Also this answer's @TuBui's question on the answer @BrDaHa provided aboveat Aug 9 '18 at 9:34.
此外，这个答案是@TuBui 在 2018 年8 月 9 日 9:34 对上面提供的答案@BrDaHa 提出的问题。
回答by Narendra Maru
To overwrite one file's content to another file. use cat eg.
将一个文件的内容覆盖到另一个文件。使用猫，例如。
echo "this is foo" > foobar.txt
cat foobar.txt
echo "this is bar" > bar.txt
cat bar.txt
Now to overwrite foobar we can use a cat command as below
现在要覆盖 foobar 我们可以使用如下的 cat 命令
cat bar.txt >> foobar.txt
cat foobar.txt
回答by aaron-coding
If you have output that can have errors, you may want to use an ampersand anda greater than, as follows:
如果您的输出可能有错误，您可能需要使用与号和大于号，如下所示：
my_task &> 'Users/Name/Desktop/task_output.log'this will redirect both stderr and stdout to the log file (instead of stdout only).
my_task &> 'Users/Name/Desktop/task_output.log'这会将 stderr 和 stdout 都重定向到日志文件（而不仅仅是 stdout）。
