I'm trying to loop through the contents of a file in zsh. In my loop I want to get user input. Going off of this answer for Bash, I'm attempting to do:
while read -u 10 line; do
echo $line;
# TODO read from stdin here, etc.
done 10<myfile.txt
However I get an error:
zsh: parse error near `10'
Referring to the 10 after the done. Obviously I'm not getting the file descriptor syntax right, but I'm having trouble figuring out the docs.
Use a file descriptor number less than 10. If you want to hard code file descriptor numbers, stick to the range 3-9 (plus 0-2 for stdin,out,err). When zsh needs file descriptors itself, it uses them in the 10+ range.
If you're even getting close to needing more than the 7 available hard coded file descriptors, you should really think about using variables to name them. Syntax like exec {myfd}<myfile.txt will open a file with zsh allocating a file descriptor greater than 10 and assigning it to $myfd.
Bourne shell syntax is not entirely unambiguous given file descriptors numbering 10 and over and even in bash, I'd advise against using them. I'm not entirely sure how bash avoids conflicts if it needs to open any for internal use - I guess it never needs to leave any open. This may look like a zsh limitation at first sight but is actually a sensible feature.