在鱼壳中管道 eval/source 的输出

Question

I want to pipe the output of eval<\/code> to a file. That works as expected if the command execution is successful:

eval ls > log.txt 2>&1
cat log.txt # Documents Desktop

Answer 1

However, I do not manage to redirect stderr if the command does not exist

That's because the output is not coming from eval or the command, it's coming from your command-not-found handler.

Try checking if the command exists before you try to execute it. If you absolutely can't, it's technically possible to silence the command-not-found error entirely by redefining __fish_command_not_found_handler :

function __fish_command_not_found_handler; end

You'd have to handle moving it back afterwards via functions --copy :

functions --copy __fish_command_not_found_handler oldcnf

Overall I don't recommend any of this and suspect you might be overusing eval .

Something that works with source would also be very much appreciated:

That's what eval is for, quite literally. Up to the upcoming 3.1 release eval is a function that's just source with some support code that mostly boils down to handling these redirections.

Answer 2

You should eval if command exists, this is possible with

test -f (whereis -b command | awk '{print $2}')

whereis -b will to search for the binaries for the command in your system

awk filter the output to only show the first result

test -f going to verify if the file exists

If the command exist, it return status 0 . So to finish you can write it like

test -f (whereis -b abcde | awk '{print $2}') && abcde > log.txt 2>&1

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Also can use this form

test (whereis -b abcde | awk '{print $2}') != '' && abcde > log.txt 2>&1