How to find contents of a file?

This should work:

find . -type f -name '*a*' -exec cat {} \; 

The less pager has a feature that allows browsing multiple files and jumping among them, so if all files are in the same directory less *a* will initially open the first, and you can at any time advance to the next file by typing :n or return to the previous file by typing :p. Typing = at any time will display the current file's name. The less pager has many other useful documented yet un-commonly used features. From within the program, type h for a long mutliple-page cheat sheet.

find -type f -maxdepth 1 -name '*a*' -exec less '{}' + 

If all files are located in the same directory, this short version will do it:

cat *a* 

In case of funny filenames starting with '-' a './' should be prefix:

cat ./*a* 

Directories with a will result in a non harmful error message.

If the files are located in one directory you can use

for i in *a*; do ( echo $i && cat $i && echo " "); done

to show all the files. Nevertheless you are still able to remember which output comes from which file and there is a seperation of the individual file output.

To output the content of all regular files in the current directory whose name contains the a character:

find . ! -name . -prune -name '*a*' -type f -exec cat {} + 

Though with several find implementations (including the GNU one on your Ubuntu), that would exclude files whose name contains byte sequences that don't form valid characters in the current locale.

With some find implementations, you can use -depth 1 instead of the standard ! -name . -prune. Some others (like GNU find) have -mindepth 1 -maxdepth 1 (though -maxdepth 1 is enough here as depth 0 is . which is excluded by both -type f and -name '*a*').

The invalid character issue could be alleviated by using zsh and:

cat ./*a*(D.) 

Which would also have the benefit of reporting an error if there's no matching file and sorting the list of files so the output is less random.

If you also want to include symlinks to regular files, add a -L option to find or - in the zsh glob qualifier.

If you want to exclude hidden files, add a ! -name '.*' to find or remove the D from zsh's glob qualifier.

Note that cat concatenates those files. If a1 contains foo without a trailing newline character (which shouldn't happen if a1 were a proper text file) and a2 contained bar, the output would be foobar.

To include the file names, you could use grep '^' /dev/null instead of cat which would prepend each line with the name of the file. Or grep -n '^' /dev/null to also include line numbers.

With the GNU implementation of head (as found on your Ubuntu), you can use head -vc-0 which would add a

===> ./file_with_a <=== 

header and an empty line between each file.