How to use a bash variable to hold the format of find's printf statement

Question

How can bash use a variable for the format of find's -printf statement? I am trying to convert the following:

find ./ -type f -printf "File: %p has modification time [%TY-%Tm-%Td %TH:%TM:%TS %TZ]\n"

which prints the following:

File: ./file_20180926_220000.txt has modification time [2018-09-26 22:00:00.0000000000 CDT]
File: ./file_20180926_210000.txt has modification time [2018-09-26 21:00:00.0000000000 CDT]
File: ./file_20180926_230000.txt has modification time [2018-09-26 23:00:00.0000000000 CDT]

I want the printf statement to be held in a variable instead, like the following illustrates (but fails).

operation="-printf \"File: %p has modification time [%TY-%Tm-%Td %TH:%TM:%TS %TZ]\n\""
find ./ -type f $operation

The output of that is:

find: paths must precede expression: %p
Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec|time] [path...] [expression]

Simpler printf formats work, like if I just use operation="-printf %p", but as soon as I use spaces in the format, I get the error above. I also tried to escape the spaces with \, but I haven't been able to get it to work.

I would like to avoid eval if possible, unless someone can suggest how to use it safely in this context.

Note: The following works, but requires two variables, while I would prefer to keep just one:

operation="-printf"
format="File: %p has modification time [%TY-%Tm-%Td %TH:%TM:%TS %TZ]\n"
find ./ -type f $operation "$format"
File: ./file_20180926_220000.txt has modification time [2018-09-26 22:00:00.0000000000 CDT]
File: ./file_20180926_210000.txt has modification time [2018-09-26 21:00:00.0000000000 CDT]
File: ./file_20180926_230000.txt has modification time [2018-09-26 23:00:00.0000000000 CDT]

score 1 · Accepted Answer · answered Sep 27 '18 at 18:50

You can store a single argument in a regular variable:

print_format="File: %p has modification time [%TY-%Tm-%Td %TH:%TM:%TS %TZ]\n"
find ./ -type f -printf "$print_format"

or you can store one or more arguments in an array:

find_options=( -printf "File: %p has modification time [%TY-%Tm-%Td %TH:%TM:%TS %TZ]\n" )
find ./ -type f "${find_options[@]}"

How to use a bash variable to hold the format of find's printf statement

1 Answers1