find inside shell function

Question

I try to put find inside function and catch an argument passed to this function with the following minimal work example:

function DO
{
    ls $(find . -type f -name "$@" -exec grep -IHl "TODO" {} \;)
}

But, when I execute DO *.tex, I get “find: paths must precede expression:”. But when I do directly:

ls $(find . -type f -name "*.tex" -exec grep -IHl "TODO" {} \;)

then I get all TeX files witch contain "TODO".

I try many thing in the DO function, such as \"$@\", '$@', I change the quotes marks, but the behavior still the same.

So, what to do to force find work inside function?

Answer 1

There are a few issues in your code:

1. The *.tex pattern will be expanded when calling the function DO, if it matches any filenames in the current directory. You will have to quote the pattern as either '*.tex', "*.tex" or \*.tex when calling the function.

2. The ls is not needed. You already have both find and grep that are able to report the pathnames of the found files.

3. -name "$@" only works properly if "$@" contains a single item. It would be better to use -name "$1". For a solution that allows for multiple patterns, see below.

The function may be written

DO () {
   # Allow for multiple patterns to be passed,
   # construct the appropriate find expression from all passed patterns

   for pattern do
       set -- "$@" '-o' '-name' "$pattern"
       shift
   done

   # There's now a -o too many at the start of "$@", remove it
   shift

   find . -type f '(' "$@" ')' -exec grep -qF 'TODO' {} ';' -print
}

Calling this function like

DO '*.tex' '*.txt' '*.c'

will make it execute

find . -type f '(' -name '*.tex' -o -name '*.txt' -o -name '*.c' ')' -exec grep -qF TODO {} ';' -print

This would generate a list of pathnames of files with those filename suffixes, if the files contained the string TODO.

To use grep rather than find to print the found pathnames, change the -exec ... -print bit to -exec grep -lF 'TODO' {} +. This will be more efficient, especially if you have a large number of filenames matching the given expression(s). In either case, you definitely do not need to use ls.

---

To allow the user to use

DO tex txt c

your function could be changed into

DO () {
   # Allow for multiple patterns to be passed,
   # construct the appropriate find expression from all passed patterns

   for suffix do
       set -- "$@" '-o' '-name' "*.$suffix"   # only this line (and the previous) changed
       shift
   done

   # There's now a -o too many at the start of "$@", remove it
   shift

   find . -type f '(' "$@" ')' -exec grep -qF 'TODO' {} ';' -print
}

Answer 2

You need to quote the parameter to the function, otherwise shell expands it and the function gets a list of files, not a wildcard mask:

DO "*.tex"

You can then use just "$1" instead of "$@", as there will only be one parameter.