I want to write several lines (5 or more) to a file I'm going to create in script. I can do this by echo >> filename. But I would like to know what the best way to do this?
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2 Answers
You can use a here document:
cat <<EOF >> outputfile
some lines
of text
EOF
answered Feb 14, 2011 at 8:42
Dennis Williamson
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3 Comments
Valentin H
+1: But works only with fixed text, not generated in script. No vars substitution etc. right?
Dennis Williamson
@Valentin: It will do variable, arithmetic and command substitution unless you suppress it by quoting the opening delimiter like this, for example:
'EOF'.
Andy T
Ive been unable to get the
- modifier to work. AS n cat <<-EOF >> out which should strip whitespaceI usually use the so-called "here-document" Dennis suggested. An alternative is:
(echo first line; echo second line) >> outputfile
This should have comparable performance in bash, as (....) starts a subshell, but echo is 'inlined' - bash does not run /bin/echo, but does the echo by itself.
It might even be faster because it involves no exec().
This style is even more useful if you want to use output from another command somewhere in the text.
1 Comment
glenn jackman
to avoid creating a subshell, you can use braces for grouping. Just remember to end the command list with a semicolon and separate the braces with spaces --
{ echo first; echo second; } >> outputfile