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edited May 6, 2022 at 21:20

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awk -F"\t" -v OFS="\t" 'NF>1 {t=$(NF-1); $(NF-1)=$NF; $NF=t} {print}' file

Do a standard swap between $NF and $(NF-1). Only only when we have at least 2 fields. It's fatal error to access field -1 (in case of empty line, NF==0).

See also: GNU awk fields

awk -F"\t" -v OFS="\t" 'NF>1 {t=$(NF-1); $(NF-1)=$NF; $NF=t} {print}' file

Do a standard swap between $NF and $(NF-1). Only when we have at least 2 fields.

awk -F"\t" -v OFS="\t" 'NF>1 {t=$(NF-1); $(NF-1)=$NF; $NF=t} {print}' file

Do a standard swap between $NF and $(NF-1) only when we have at least 2 fields. It's fatal error to access field -1 (in case of empty line, NF==0).

See also: GNU awk fields

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answered May 6, 2022 at 21:12

thanasisp

8.5k
2
29
40

awk -F"\t" -v OFS="\t" 'NF>1 {t=$(NF-1); $(NF-1)=$NF; $NF=t} {print}' file

Do a standard swap between $NF and $(NF-1). Only when we have at least 2 fields.