I want to use a shortcut command for printf with a specific format string, and came up with the following.
local PF="printf %s\n"
$PF "Some Text"
It does the job, but wonder if there exist any caveats when using such an approach, that could lead to misinterpretation of the format string.
Why execute the value of a variable when you could just use a function - that's what they're for.
PF() { printf "%s\n" "$@" ; }
PF "Some Text"
or an alias:
alias PF='printf "%s\n"'
PF "Some Text"
If you really want to have a variable involved, use it to hold the format string. e.g.
fmt="%s\n"
printf "$fmt" "Some Text"
If you want to keep the line lengths under, say, 80 chars, then assign the variable in two or more statements. e.g.
fmt="......part1......"
fmt+="......part2......"
fmt+="......part3......"
...
This is also useful if you just want to make assigning the format string more readable, or to add individual comments about some or all of the parts.
printf and fmt).
fmt="...73 chars..." then fmt+="...another 72 chars" (repeat as needed). number of chars will vary according to indentation and other factors that might affect the positioning of the fmt=" and fmt+=" portions of the line (and the ending quote, of course).
That $PF in list context is invoking split+glob. The contents of $PF is split according to complex rules involving the $IFS special parameters (which have nothing to do with what happens when bash interprets the printf %s\n code for instance), and then the resulting words are subject to filename generation (aka pathname expansion aka globbing).
So, here, there are at least 2 problems:
the behaviour of that $PF is dependant on the current value of $IFS. By default, in bash, $IFS contains space, tab and newline, and here you do want $PF to be split on space, and the string otherwise doesn't contain tab nor newline. But in a context where $IFS has been changed to % for instance, you'd end up running the "printf " command with "s\n" as argument.
In some versions of bash (namely 5.0, I believe it was reverted in 5.1), \ is a globbing operator (at least like here where it comes from some parameter expansion and is not otherwise used for quoting).
With failglob or nullglob options on, that would mean:
$ PF='printf %s\n' bash-5.0 -O failglob -c '$PF test'
bash-5.0: no match: %s\n
$ PF='printf %s\n' bash-5.0 -O nullglob -c '$PF test%d'
test0
And even without those options:
$ PF='printf %s\n' bash-5.0 -c '$PF test'
test
$ touch %sn
$ PF='printf %s\n' bash-5.0 -c '$PF test'
testn
See @cas' fine answer for what to do instead.
%s\n. Also, you're likely to run into all sorts of quoting-related annoyances by trying to do this with a variable.