Text Processing – Split File at a Pattern

awksedsplittext processing

How to split a large file into two parts, at a pattern?

Given an example file.txt:

ABC
EFG
XYZ
HIJ
KNL

I want to split this file at XYZ such that file1 contains lines up-to XYZ and rest of the lines in file2.

Best Answer

With awk you can do:

awk '{print >out}; /XYZ/{out="file2"}' out=file1 largefile


Explanation: The first awk argument (out=file1) defines a variable with the filename that will be used for output while the subsequent argument (largefile) is processed. The awk program will print all lines to the file specified by the variable out ({print >out}). If the pattern XYZ will be found the output variable will be redefined to point to the new file ({out="file2}") which will be used as target to print the subsequent data lines.

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