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How to concatenate multiple lines of output to one line?

If I run the command cat file | grep pattern, I get many lines of output. How do you concatenate all lines into one line, effectively replacing each "\n" with "\" " (end with " followed by space)?

cat file | grep pattern | xargs sed s/\n/ /g isn't working for me.

Solution

  • Use tr '\n' ' ' to translate all newline characters to spaces:

    $ grep pattern file | tr '\n' ' '

    Note: grep reads files, cat concatenates files. Don't cat file | grep!

    Edit:

    tr can only handle single character translations. You could use awk to change the output record separator like:

    $ grep pattern file | awk '{print}' ORS='" '

    This would transform:

    one
two 
three

    to:

    one" two" three"