Use xargs to build and run a command list

Question

How to use xargs to build and run a command list such as these:

#1
cmd1 <arg1> && cmd2 <arg1> && cmd3 <arg1>
#2
cmd1 <arg1> ; cmd2 <arg1>

Answer 1

By starting a child shell for each line of input to xargs:

xargs -I {} sh -c 'cmd1 "$1" && cmd2 "$1" && cmd3 "$1"' sh {}

xargs -I {} sh -c 'cmd1 "$1"; cmd2 "$1"' sh {}

This runs sh -c which executes the given string as a shell script. The arguments to sh -c, after the script itself, are given to $0 and $1 inside the script. The value of $0 should usually be the name of the shell, which is why we pass sh as this argument (it will be used in error messages).

Alternatively,

xargs sh -c '
    for arg do
        cmd1 "$arg" && cmd2 "$arg" && cmd3 "$arg"
    done' sh

xargs sh -c '
    for arg do
        cmd1 "$arg"
        cmd2 "$arg"
    done' sh

These variations will take as many arguments as possible and then apply the code to these in a loop inside the sh -c scripts.

As always when using xargs, care must be taken so that the arguments supplied to the given utility (sh -c here) are delimited properly.