UUOC apparently is/was a thing: useless use of cat
Posted by jpluimers on 2021/08/16
A while ago I bumped into UUOC: [WayBack] cat (Unix): Useless use of cat – Wikipedia.
For me the post important reason to choose between cat and a redirect is realising from the above article:
- input redirection forms allow command to perform random access on the file, whereas the
catexamples do not. catwritten with UUOC might still be preferred for readability reasons, as reading a piped stream left-to-right might be easier to conceptualize
I ended up at UUOC through [WayBack] bash – Calling multiple commands through xargs – Stack Overflow.
Invoking multiple commands with the same xargs parameter.
The above question also led me to two better solutions for my original xargs problem.
I liked both below solutions.
The first (by [WayBack] ckhan) uses sh as subshell and substitutes the parameter with a readable name.
The second (by [WayBack] shivams) uses a function which gets way more readable code when the command-line gets longer.
[WayBack] shell – xargs : using same argument in multiple commands – Unix & Linux Stack Exchange:
- you’ll want to explicitly execute a subshell:
echo 95 | xargs -n1 -I_percent -- sh -c '[ _percent -ge 95 ] && echo "No Space on disk _percent% full -- remove old backups please"'Note also I’m using
_percentinstead of{}to avoid extra quoting headaches with the shell. It’s not a shell variable; still just an xargs replacement string.- An alternative way, which is more readable, is to define a separate function which contains all your other commands and then call that function with
xargsin a sub-shell.Hence, for example:myfunc(){ [ "$1" -ge 95 ] && echo "No Space on disk $1% full -- remove old backups please" echo "Another command echoing $1" } export -f myfunc echo 95 | xargs -n1 -I_percent -- sh -c 'myfunc "_percent"'
–jeroen
The Wiert Corner - irregular stream of stuff 
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