问题
If I'm in terminal and I write some basic string to a file, is there a way to continually append to that file using echo?
For instance, echo 'hello' > file will put 'hello' into that file, but what if I now want to append ' world' to file? I know that if I do echo ' world', it'll overwrite the first string I wrote into file. Is there any += operator I can use in bash?
EDIT: Nevermind, I can append using >>. Is it possible to append to the same line instead of to a new line?
回答1:
echo -n 'Hello' > file
echo ', World!' >> file
The >> redirection operator means "append."
Here we're using a non-standard extension of echo, where -n tells it not to append a new line.
If you want standard-compliant behavior, use printf:
printf 'Hello' > file
printf ', World!\n' >> file
Edit: using double quote around a string containing the exclamation ! may not work with some versions. It could get interpreted as a history expansion token. Use single quotes to prevent this.
来源：https://stackoverflow.com/questions/43675379/echo-appending-text