How to append to the end of a line before the first pattern match?

reno_queen

I have a file containing some random data like: number1 number2 number3 &END I want to add a \ to the end of the line containing number3, but I cannot match a pattern on that line as that number keeps changing. So I try matching "&END" in sed and then append a line before it, but that does not work for me because it creates a new line, like number1 number2 number3 \ &END My desired output is number1 number2 number3 \ &END Also, I only need to...

Originally asked by Pauling0304 on Stack Exchange (askubuntu) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

You can use sed -z and include \n in your pattern: -z, --null-data separate lines by NUL characters sed -Ez 's/(\n+&END)/ \\\1/' file sed by default replaces only the first occurency per line. As you have only one line if you use NUL-delimiter, you're fine. -E tells sed to use Extended Regex (ERE) instead of Basic Regex (BRE). You can omit the flag, but then you need to escape the braces: sed -z 's/\(\n+&END\)/ \\\1/' file Output: &COORD 1.4089452021105357E+01 1.3165670625576730E+01 1.2727066323166799E+01 \ ... ... 1.3549295360587577E+01 1.2120902691780184E+01 1.2741652733169291E+01 \ &END ... ... &COORD H 3475843 73457834 7346587435 ... ... &END Note, -z is fine in Ubuntu, but not...

Full answer by pLumo: https://askubuntu.stackexchange.com/a/1378483 (CC BY-SA 4.0).

Need it done for your business? UphillTech.