Suppose I have a file with this content
2:33:4:F:T:Y
1:10:0:A:B:C:D:E:F:G:
how to change F in second line to R for multiple files using sed?
The desired output would be:
2:33:4:F:T:Y
1:10:0:A:B:C:D:E:R:G:
Edit:
the change should be only in second line of every file, the fields delimited by : so i need the 9th field to be changed, and ignore if the filed have anything but only F.
With awk :
Replace every 2nd line on each file and also on 9th field F to R
$ awk 'BEGIN{FS=OFS=":"} FNR==2{ sub(/^F$/,"R",$9); }1' file1 file2
2:33:4:F:T:Y
1:10:0:A:B:C:D:E:R:G:
2:33:4:F:T:Y
1:10:0:A:B:C:D:E:R:G:
With awk:
$ awk -F: -vOFS=: '($9=="F" && NR==2){$9="R"}1' file
2:33:4:F:T:Y
1:10:0:A:B:C:D:E:R:G:
For many files, do:
for file in *; do
awk -F: -vOFS=: '($9=="F" && NR==2){$9="R"}1' "$file" > newfile &&
mv newfile "$file"
done
Or, with newer versions of GNU awk:
gawk -iinplace -F: -vOFS=: '($9=="F" && FNR==2){$9="R"}1' file.*
-F : and -v OFS=: so they conform to the standards? (Please correct me in case I'm wrong.)
-F and -v are followed by space.
F? Should all other lines be ignored? Are fields defined by:? Can the field beFRor anything else that includesF?