How to execute command line via input

Question

I've read this and this, but didn't make it work.

Here's my script:

env -i MY_KEY=$my_key MY_ACCOUNT=$my_account command-that-outputs-a-list \
    | grep "name" | awk -v src=$src \
    '{a = substr($2,2, length($2)-3); print "my_copy_cmd -s xx-yy/"src"/"a" -d . "}'

and it output things like:

my_copy_cmd -s xx-yy/source-file-name -d .
my_copy_cmd -s xx-yy/source-file-name -d .
my_copy_cmd -s xx-yy/source-file-name -d .
my_copy_cmd -s xx-yy/source-file-name -d .

Now I'd juste like to execute it in the same line, but xargs makes all incoming into one line of arguments (and it doesn't run it). xargs -0 doesn't work either. And I'd like to run it using env -i to run it in an environment without variables, and to set temporarily my env variables (= like I did at the very first command), something like (which doesn't work):

env -i MY_KEY=$my_key MY_ACCOUNT=$my_account command-that-outputs-a-list \
    | grep "name" | awk -v src=$src \
    '{a = substr($2,2, length($2)-3); print "my_copy_cmd -s xx-yy/"src"/"a" -d . "}' \
    | xargs env -i MY_KEY=$my_key MY_ACCOUNT=$my_account

Ron · Accepted Answer · 2020-08-28 15:12:02Z

1

Does this work:

env -i MY_KEY=$my_key MY_ACCOUNT=$my_account command-that-outputs-a-list \
    | grep "name" | awk -v src=$src \
    '{a = substr($2,2, length($2)-3); print "my_copy_cmd -s xx-yy/"src"/"a" -d . "}'|while read z;do $z 2>&1 ;done

The while loop will read each whole line from the output, and just execute it.

edited Aug 28, 2020 at 15:12

answered Aug 28, 2020 at 9:53

Ron

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7 Comments

Olivier Pons Over a year ago

It just does this once = the first line

Ron Over a year ago

If you try to debug with |while read z;do echo $z;done does it give you all of the lines again? If it does, then I would assume your first execution of my_copy_cmd exits with an error, which somehow prevents the rest of the copy commands to run.. or right after the run of the whole command use echo $? to see if the result is 0

Olivier Pons Over a year ago

Yes, it gives me all the "transformed lines" again (ready to be executed!) and the result of echo $? is 0

Ron Over a year ago

If the echo $z gives the proper output, which is the same as the one you see above, then the while loop parses each line properly.. now why your my_copy_cmd is not executing, I do not have enough details to say. If you manually execute in your shell the my_copy_cmd does it work ? with all the parameters? and the echo $? after it is again 0 ?

Olivier Pons Over a year ago

It's very strange: if I copy / paste line by line they work, but if I copy the whole lines then paste them in a shell, only the first one is executed. FYI it's launching az (azure command utility) under Linux

|

Thomas · Accepted Answer · 2020-08-28 09:54:32Z

Try piping the output into sh or bash. You can set variables by adding the assignment before the command:

$ echo 'echo variable is $my_var' | my_var=foo bash
variable is foo

So something like this should work:

env -i MY_KEY=$my_key MY_ACCOUNT=$my_account command-that-outputs-a-list \
    | grep "name" | awk -v src=$src \
    '{a = substr($2,2, length($2)-3); print "my_copy_cmd -s xx-yy/"src"/"a" -d . "}' \
    | MY_KEY=$my_key MY_ACCOUNT=$my_account bash

I find that this is a pretty good trick to assemble and preview a batch of commands before actually executing them.

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