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I have a directory hierarchy named, for example, abc and a text file names.txt. I need to choose several lines from the text file and then create new files with sample text, say "Hello world", in every sub-directory of the abc, where every chosen line from the names.txt is the name for one of the new files. I have to do it in one line using xargs or -exec. I've tried something like this but it doesn't seem to work:

find abc -type d -exec sh -c 'grep ^'A' names.txt | xargs -I% sh -c 'echo 'Hello world' | tee {}/%'' \;

How to do this the right way?

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  • What "doesn't work" about it, exactly? – Jeff Schaller♦ Dec 12 '18 at 12:06
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Let's start with what you need to for one directory:

awk '/^A/ { print "Hello world" >$0 }' names.txt

This would read the file called names.txt and write the string Hello world to each filename given by a complete line of input from that file, if the input line starts with a capital A.

With a small modification, we can get it to output to a file under a specific directory, $dirname:

awk -v dir="$dirname" '/^A/ { print "Hello world" >(dir "/" $0) }' names.txt

We may then use find to call this for each subdirectory (including the start directory):

find abc -type d -exec awk -v dir={} '/^A/ { print "Hello world" >(dir "/" $0) }' names.txt \;
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  • @StéphaneChazelas Yes, print >(expression) appears to work. – Kusalananda♦ Dec 12 '18 at 13:30
  • @StéphaneChazelas The issue with using -execdir here is that the names.txt file has to be given with an absolute pathname. That's not difficult to organize though... – Kusalananda♦ Dec 12 '18 at 13:32
  • Ah OK, sorry, I thought the names.txt was to be found in each directory. Then that won't work. With -execdir, the command runs in the parent of the file being found (hence the -name names.txt -execdir...). – Stéphane Chazelas Dec 12 '18 at 13:36
  • @StéphaneChazelas In, the parent, of course. Doh. – Kusalananda♦ Dec 12 '18 at 13:38
  • Note that the dir={} assumes a version of find that expands {} when found as part of arguments, and that directory names don't contain backslash characters. – Stéphane Chazelas Dec 12 '18 at 14:01

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