Bash - Strings, Commands and Escaping (oh, my!)

Question

I\'m wasting so much time right now trying to figure out something so simple....

pseudo code (mixture of several syntax\'s, sorry):

cmd1 = \"find          


        

Answer 1

Short form: Expanding $foo unquoted runs the content through string-splitting and glob expansion, but not syntactical parsing. This means that characters which would do quoting and escaping in a different context aren't honored as syntax, but are only treated as data.

If you want to run a string through syntactical parsing, use eval -- but mind the caveats, which are large and security-impacting.

Much better is to use the right tools for the job -- building individual simple commands (not pipelines!) in shell arrays, and using functions as the composable unit for constructing complex commands. BashFAQ #50 describes these tools -- and goes into in-depth discussion on which of them is appropriate when.

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To get a bit more concrete:

nl=( nl -ba -s'  ' )
find_output=$(find "$log_dir" -type f -mtime "+$arch_age" | grep -v -f "$exclude" | "${nl[@]}")
printf "%s\n" "$find_output"

...would be correct, since it tracks the simple command nl as an array.