shell script printf meaning

Question

Inside a for loop (i) I have to test:

if [[ "${PARAMETER[$i]}" =~ $(printf "|^%s\$" "${COMMANDS[@]" | cut -c 2-)]]; then....

And my doubt is in the printf part. Sorry if it is not well explained.

the printf-part together with a command-execution and a pipe produces a formatted string consisting of the the content of the array COMMANDS that is compared to an item in an array PARAMETERS. Run the printf part separately in a shell to see what it does. What part do you have doubts about? — Fredrik Pihl
– Fredrik Pihl, Commented Oct 22, 2013 at 9:54

Jens · Accepted Answer · 2013-10-22 09:53:29Z

1

The POSIX printf function works almost like its C counterpart. Here, the %s is replaced with whatever "${COMMANDS[@]" expands to. The result has a |^ prepended, and a $ appended.

If "${COMMANDS[@]" expands to multiple tokens, the result is the concatenation of all such strings.

Note: did you forget a blank before the ]]?

answered Oct 22, 2013 at 9:53

Jens

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