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I have a list of directories in a text file, wherein I want to find and change files that share a particular naming convention.

example file: 

dir1
dir2
dir3

example folder structure with files

dir1/
   thing.txt
   thing.blah
dir2/
   rar.txt
   thing.blah
dir3/
   apple.txt
   another.text.file.txt
   thing.blah

First, I find the name of the .txt, but then I want to perform a change on it. For example, i want to perform a sed command on thing.txt, rar.txt and apple.txt, but not another.text.file.txt.

My question is, once I have all the file names, how do I perform a command on the files with those names? How can I then take those lines of text such as:

cat dirFile.txt | xargs ls | grep <expression>.txt 
    thing.txt
    rar.txt
    apple.txt
 !cat | some command

and run an action on the actual files under the directories?

What I'm getting is the above result,

But what I need is 

dir1/thing.txt
dir2/rar.txt
dir3/apple.txt
nanthil
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  • Why not `another.text.file.txt`? – John Kugelman Apr 27 '16 at 22:06
  • what I'm trying to get is file itself in `dir1/thing.txt dir2/thing.txt` etc, if I could write that to a file, that'd be fine, but I can't figure out how to get which dir which file is in, so that I operate on the correct file. If I could get that list, then I could do it in line anyway, and wouldn't need to write it to a file.... – nanthil Apr 27 '16 at 22:23
  • try using find. find -name *.txt > myfilelist – user5976242 Apr 27 '16 at 22:35
  • or find -regex .txt > myfilelist – user5976242 Apr 27 '16 at 22:42
  • @user5976242 "**I have a list of directories in a text file**" – Pedro Lobito Apr 28 '16 at 00:15
  • I understood that, OP wanted to use xargs. cat dirs.txt |xarg -I % find % -name *.txt or -regex – user5976242 Apr 28 '16 at 00:44
  • Possible duplicate of [How to pipe output from grep to cp?](https://stackoverflow.com/q/33140583/608639), [Is there a grep equivalent for find's -print0 and xargs's -0 switches?](https://stackoverflow.com/q/15976570/608639), etc. – jww Nov 04 '19 at 19:27

2 Answers2

2

Say you have a file named dirs which have all directories you need to search:

while IFS= read -r i; do
  find "$i" -name '<expression>' -print0
done < dirs | xargs -0 some_command

If you know the directories doesn't have spaces or another type of separators you can simplify a bit:

find $(<dirs) -name '<expression>' -print0 | xargs -0 some_command

Perhaps your some_command expect only one file at a time, in this case use -n1:

... | xargs -0 -n1 some_command

or move some_command to find itself:

find $(<dirs) -name '<expression>' -exec some_command {} \;
  • $(<dirs) is a comand substitution. It reads the content (like cat) of dirs file and use it as the first arguments of find. Empty dirs is safe on GNU find (eg Linux) but you need at least one line - which is converted as one argument - on BSD (eg Mac OS X)
  • -print0 separates files with null
  • -0 expects these null chars.
  • -n1 says xargs to send only one argument to some_command
Joao Morais
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1

I guess my comments were not adequately expressed. to get the output you desire;

cat dirfile.txt | xargs -I % find % -name <your file spec> or -regex <exp>
user5976242
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