using find command in unix to search for a newline

Question

I would like to search all .java files which have the newline escape sequence \n (backslash followed by 'n') in the files.

I am using this command:

find . –name "*.java" –print | xargs grep “\n”

but the result shows all lines in .java files having the letter n. I want to search for a newline \n.

Can you please suggest a solution?

Example:

x.java
method abc{
String msg="\n Action not allowed.";}

y. java
method getMsg(){
String errMsg = "\n get is not allowed.";}

I want to search all *.java files having these type of strings defined with newline escape sequence.

\n is newline; \r is carriage return. What are you after? — Jonathan Leffler
– Jonathan Leffler, Commented Dec 19, 2013 at 6:06
On Unix systems, every line in every file ends with a newline, by definition. A line is a sequence of characters terminated by a newline. Even in a binary file (.class file or object file), lines are interpreted as a sequence of characters up to the next newline character (even if there are millions of characters in total, including zero or null bytes). — Jonathan Leffler
– Jonathan Leffler, Commented Dec 19, 2013 at 6:47

Mark Plotnick · Accepted Answer · 2013-12-19 13:19:41Z

1

It looks like you want to find lines containing the 2-character sequence \n. To do this, use grep -F, which treats the pattern as a fixed string rather than as a regular expression or escape sequence.

find . –name "*.java" –print | xargs grep -F "\n"

edited Dec 19, 2013 at 13:19

answered Dec 19, 2013 at 9:43

Mark Plotnick

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oyss · Accepted Answer · 2013-12-19 06:46:43Z

0

This -P grep will match a newline character. using '$'. Since each line in my file contains a newline ,it will match every line.

grep -P '$' 1.c

I don't know why you want to match a newline character in files.That is strange.

answered Dec 19, 2013 at 6:46

oyss

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2 Comments

sailaja kasanur Over a year ago

I have many string messages defined as "\n xxx" in many .java files. These messages will be displayed during exceptions. I want to search all the strings messages which are defined starting with \n

oyss Over a year ago

@sailajakasanur Then you should give us a exact example of the line you want to match.If your newline character is written in "\n".you can use grep -P "\\\n" e.g: echo "\n xxx"|grep -o -P "\\\n" to match "\n". sorry i don't use tcsh,don't know if it supports perl regex.

janos · Accepted Answer · 2013-12-19 09:54:49Z

0

I believe you're looking for this:

find . –name "*.java" –exec grep -H '"[^"]*\n' {} \;

The -H flag is to show the name of the file when there was a pattern match. If that doesn't work for you:

find . –name "*.java" –print0 | xargs -0 grep '"[^"]*\n'

If xargs -0 doesn't work for you:

find . –name "*.java" –print | xargs grep '"[^"]*\n'

If grep doesn't work for you:

find . –name "*.java" –print | xargs egrep '"[^"]*\n'

I needed this last version in Solaris, in modern systems the first one should work.

Finally, not sure if the pattern covers all your corner cases.

answered Dec 19, 2013 at 9:54

janos

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