awk - Spliting a file into multiple files based on common line prefix -


suppose have file following format.

prefix1: line 1 prefix1: line 2 prefix1: line 3 prefix2: line 4  prefix2: line 5 prefix3: line 6  prefix3: line 7 prefix3: line 8 prefix3: line 9 prefix3: line 10

i split 3 files names prefix1, prefix2, prefix3, newlines intact part of whichever file either entirely contains them.

in real file, there might n prefixes , not 3.

i write python script implement functionality directly, wonder if there's shorter way in awk.

this one-liner works job:

 awk -f: '{f=$1?$1:f; print > f}' file

with example:

kent$  cat file prefix1: line 1 prefix1: line 2 prefix1: line 3 prefix2: line 4  prefix2: line 5 prefix3: line 6  prefix3: line 7 prefix3: line 8 prefix3: line 9 prefix3: line 10  kent$  awk -f: '{f=$1?$1:f; print > f}' file  kent$  head prefix* ==> prefix1 <== prefix1: line 1 prefix1: line 2 prefix1: line 3  ==> prefix2 <== prefix2: line 4  prefix2: line 5  ==> prefix3 <== prefix3: line 6  prefix3: line 7 prefix3: line 8 prefix3: line 9 prefix3: line 10

you mentioned n prefixes. if n large enough, above awk line fail "opened many files". solve it, close file after write/append text it.

that , line :

awk -f: '{f=$1?$1:f; print >> f; close(f)}' file

this line works no matter input file sorted prefix or not.


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