How to do max-depth search in ack and grep?

Question

Is there any way to tell ack to only search for text on the current folder? (or specify a max-depth level?) And with grep?

Answer 1

You can couple find with the -exec argument. Example:

find . -maxdepth 1 -exec grep foo {} \;

This can be scaled, i.e. -maxdepth 2.

Edit

As mentioned in the [answer by @Stéphane Chazelas], it is advisable to restrict find to regular files so that grep doesn't produce an error when the argument {} actually is a directory path:

find . -maxdepth 1 -type f -exec grep -H foo {} \;

• -type f is a filter for find that limits the search results to files
• -H is a grep option used to print a filename for every match (desired behavior when more than one file match)

Answer 2

Use -n for no-recurse:

$ ack -n foo

grep is not recursive by default, and you should use the -r flag only if you want a recursive search.

You can search the current directory with grep as follows:

$ grep -- foo *

Answer 3

For an equivalent of GNU grep -r foo . that looks only in regular files in the current directory and not any of the subdirectories, you can do:

• zsh and GNU grep or compatible:

  grep -H foo ./*(.D)
  

• standard find and grep from any shell:

  find . ! -name . -prune -type f -exec grep foo /dev/null {} +
  

• GNU find and GNU grep (or compatible) from any shell:

  find . -maxdepth 1 -type f -exec grep -H foo {} +
  

To look for files at depths 1 to 3 (in ./file, ./subdir/file, ./subdir/subsubdir/file, but not any deeper):

• GNU find and GNU grep (or compatible) from any shell:

  find . -maxdepth 3 -type f -exec grep -H foo {} +
  

• standard find and grep, but assuming file names are valid text in the locale:

  find . '(' ! -path './*/*/*' -o -prune ')' -o -exec grep foo /dev/null {} +
  

• zsh and GNU grep or compatible:

  set -o extendedglob # best in ~/.zshrc
  grep -H foo ./**/*~./*/*/*/*(D.)
  

  though note that it's inefficient as it still looks for files at any depth before excluding them with the ~ extendedglob operator.

-H (GNU extension) / /dev/null is to make sure grep prints the name of the file even if only one file is given to it.

-type f or zsh's . glob qualifier is to select only regular files (like GNU grep does by default with -r nowadays), to the exclusion of all other types of files such as symlinks (even if they point to regular files), directories, fifos, devices...

Answer 4

I'm obviously late to the topic, but this may prove useful to a future reader. After reading the comments and answers above, perhaps a wrapper script for grep is in order until GNU find gains a -maxdepth option. Using a pattern like the following,

 grep -Hin foo `find . -maxdepth 1 -type f`

the following script will effectively wrap the pair of commands:

#! /bin/sh
#
# USAGE: grep-maxdepth <NUM> <GREP_ARGS>
#
#    <NUM>        integer specifying the maxdepth passed to find
#    <GREP_ARGS>  arguments provided to grep
#
depth=$1
shift
# DON'T DO THIS ! grep $* `find . -maxdepth ${depth} -type f`
# DO this based upon comments
find . -maxdepth ${depth} -type f -exec grep $* {} \;

This solution should work regardless of the availability of GNU grep; however, the usage of -maxdepth for find implies the installation of GNU's Tools.

I don't use ack, but this simple solution should work for it as well.

NOTE: Trivially-edited based upon comment from Stéphane Chazelas. This should now properly-accommodate white space and other characters in file names. Thanks.