I want to remove all empty lines from a file. Even if the line contains spaces or tabs it should also be removed.
grep for non-blanks:
grep '[^[:blank:]]' < file.in > file.out
[:blank:], inside character ranges (
[...]), is called a POSIX character class. There are a few like
[:blank:] matches horizontal white space (in the POSIX locale, that's space and tab, but in other locales there could be more, like all the Unicode horizontal spacing characters in UTF8 locales) while
[[:space:]] matches horizontal and vertical white space characters (same as
[:blank:] plus things like vertical tab, form feed...).
Would return the lines that contain any of the characters,
k. Character classes are only recognised within
[...] negates the set. So
[^[:blank:]] means any character but the blank ones.
sed -e 's/^[[:blank:]]*$//' source_file > newfile
sed -e '/^[[:blank:]]*$/d' source_file > newfile
For each line, substitute:
- if it starts ("
- with spaces or tabs ("
[[:blank:]]") zero or more times ("
- and then is the end of the line ("
More info on ::blank:: and other special characters at http://www.zytrax.com/tech/web/regex.htm#special
Use the following command:
grep '\S' FILE
which removes all lines including spaces or tabs.
Otherwise, removal not including lines with spaces/tabs, use:
grep . FILE
$ printf "line1\n\nline2\n \nline3\n" > FILE $ cat -v FILE line1 line2 line3 $ grep '\S' FILE line1 line2 line3 $ grep . FILE line1 line2 line3
- Removal including space/tab lines: How to remove empty/blank lines in a file in Unix?
sed: Delete empty lines using sed
awk: Remove blank lines using awk
strings looks at line-endings as something not-a-string.
cat file.txt | strings
...and all empty lines are gone.