linux - awk command issue to recognize delimiter -

experts, thoughts why delimiter not working in case? '^a' real '^a' string, not ascii value 1.

cat 2.txt 123^a9343784^a2207983400 45^a1270843^a66789439 67^a188285^a28075164 8^a91183^a27049564 9^a128589^a7283486 100^a84325^a7043462  cat 2.txt | awk -f'^a' '{print $1 }' 123^a9343784^a2207983400 45^a1270843^a66789439 67^a188285^a28075164 8^a91183^a27049564 9^a128589^a7283486 100^a84325^a7043462 

btw, working on mac osx/linux.

thanks in advance, lin

edit

after valid points made ed morton in comments area, have updated answer provide more insight on different behavior of awk variants regarding escaping.

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my understanding want use ^a delimiter.

you have escape ^ character, messes awk's regex*. way this, prepending double escape sequence \\ ^

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- in linux (awk symlinked mawk or gawk, see note):

$ cat 2.txt | awk -f'\\^a' '{print $1 }' # mawk, gawk 

now, mawk has more relaxed behavior on this, possible achieve same results using \ (single escape):

$ cat 2.txt | awk -f'\^a' '{print $1 }' # mawk (note single backslash here) 

however, in general, should avoided (especially if used in script or passe partout one-liner -portability comes mind-), since other awk variants treat differently , variety of unwanted outcomes occur (some well-disguised legitimate ones in complex situations)

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- in windows (cygwin, mingw, gnutils provide gawk):

$ cat 2.txt | awk -f'\\^a' '{print $1 }' # gawk 

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- in osx (awk default nawk):

$ cat 2.txt | awk -f'\\^a' '{print $1 }' # nawk 

all these yield:

123 45 67 8 9 100 

* you can find more information on awk's regular expressions here.

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note

in order find variant of awk available in system, first have locate awk command , use ls follow link chain actual binary, this:

$ awk /usr/bin/awk $ ls -l /usr/bin/awk lrwxrwxrwx 1 root root ... /usr/bin/awk -> /etc/alternatives/awk $ ls -l /etc/alternatives/awk lrwxrwxrwx 1 root root ... /etc/alternatives/awk -> /usr/bin/mawk 

(example taken system, xubuntu 14.04)