grep(1) -Rin --exclude="*.{jpg,png,gif}" "mot composé" ./*
print lines matching a pattern
-R, -r, --recursive
       Read all files under each directory, recursively; this is equivalent to the -d recurse option.
-i, --ignore-case
       Ignore case distinctions in both the PATTERN and the input files.  (-i is specified by POSIX.)
-n, --line-number
       Prefix  each  line of output with the 1-based line number within its input file.  (-n is specified
       by POSIX.)
       Skip files whose base name matches GLOB (using wildcard matching).  A file-name glob can use *, ?,
       and [...]  as wildcards, and \ to quote a wildcard or backslash character literally.
grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus
(-) is given as file name) for lines containing a match to the given PATTERN.  By  default,  grep  prints
the matching lines.
source manpages: grep