If you supply the shell command xargs with the right commands, it will function the same way as a for loop. But more like a functional map command.
Normally xargs will execute a provided command once and append everything from pipe as arguments:
> echo 1 2 3 4 | xargs echo These arguments were provided: These arguments were provided: 1 2 3 4
Adding the parameters -n 1 will execute the command time for each 1 piped arguments.
> echo 1 2 3 4 | xargs -n 1 echo Run for each argument: Run for each argument: 1 Run for each argument: 2 Run for each argument: 3 Run for each argument: 4
If your variable argument for the command is the last argument, this will work fine.
But if not.
xargs has the parameter -I.
Unfortunately this parameter make the command work different:
> echo 1 2 3 4 | xargs -n 1 -I {} echo Run with {} as argument Run with 1 2 3 4 as argument
-n 1 no longer works...
There is a work around.
A delimiter has to be given.
In the example it will be space: -d " ".
However, -d messes up the delimiter by not striping aways other white spaces.
When using echo, a newline character will be put at the end of the arguments.
We can remove any newline from the xargs input by using an additional before our intended xargs:
> echo 1 2 3 4 | xargs echo -n | xargs -d " " -I {} echo Run with {} as argument Run with 1 as argument Run with 2 as argument Run with 3 as argument Run with 4 as argument
Here, the part xargs echo -n will take all piped incoming arguments and print them space separated and -n will prevent a newline character from being printed at the end.