1

After answering this question, I am now wondering the best way to further process the null-separated output of find -print0.

The following command would search for a phrase in the first 10 files that find returns - maybe we don't want to search too many at one time.

find . -maxdepth 1 | head -10 | xargs grep "Specific Phrase"

However, if there are newlines or spaces in the filenames, this can become a challenge as they will mess up our xargs command.

How could I write the following so it works - can I do this in bash or do I need to use a tool like awk to break this string up at the nulls?

find . -maxdepth 1 -print0 | head -10 | xargs -0 grep "Specific Phrase"

It seems the other words I could use to describe this is how to change the field separator to be a null character.

Improve this question
4
  • Which shell? The facilities for this are far better in bash or ksh than POSIX sh. Commented Feb 25, 2016 at 0:21
  • I realized I didn't know how to do it in any shell. Lets say bash as it is very common. Commented Feb 25, 2016 at 0:24
  • That was kind of a "leading comment", as the solution @CharlesDuffy provided below is implemented in bash, but the question mentioned only tools that are external to most shells. I would love to see a Charles-approved shell-agnostic answer to this question, or at least one that works in a POSIX shell. Commented Feb 25, 2016 at 12:49
  • I posted an awk answer below as well that does not require complex shell machinations. Commented Feb 26, 2016 at 15:57

2 Answers 2

Reset to default
2

In bash, you could do something like the following:

head0() { local item i=0 while IFS= read -r -d '' item && (( ++i <= "$1" )); do printf '%s\0' "$item" done } find . -maxdepth 1 -print0 | head0 10 | xargs -0 grep "Specific Phrase"

The relevant idioms here are IFS= read -r -d '' item to read, and printf '%s\0' "$item" to write.

To explain that read command in detail:

  • IFS= prevents whitespace from being trimmed from either the beginning or end of any string
  • read -r prevents literal backslashes from being consumed or suppressed.
  • -d '' sets the first character of the string '' -- an empty NUL-delimited string, of which the first character is thus NUL -- as the character which will terminate the read.
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

2

Here is another possible option using awk, which was presented as part of an answer to this question but is also applicable here.

find . -maxdepth 1 -print0 \ | awk 'NR<=10;NR>10{exit}' RS="\0" ORS="\0" \ | xargs -0 grep "Specific Phrase"
Improve this answer

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.