I encountered a problem with bash, I started using it recently. I realize that lot of magic stuff can be done with just one line, as my previous question was solved by it. This time question is simple:
I have a file which has this format
2 2 10
custom
8 10
3 5 18
custom
1 5
some of the lines equal to string custom (it can be any line!) and other lines have 2 or 3 numbers in it.
I want a file which will sequence the line with numbers but keep the lines with custom (order also must be the same), so desired output is
2 4 6 8 10
custom
8 9 10
3 8 13 18
custom
1 2 3 4 5
I also wish to overwrite input file with this one. I know that with seq I can do the sequencing, but I wish elegant way to do it on file.
You can use awk like this:
awk '/^([[:blank:]]*[[:digit:]]+){2,3}[[:blank:]]*$/ {
j = (NF==3) ? $2 : 1
s=""
for(i=$1; i<=$NF; i+=j)
s = sprintf("%s%s%s", s, (i==$1)?"":OFS, i)
$0=s
} 1' file
2 4 6 8 10
custom
8 9 10
3 8 13 18
custom
1 2 3 4 5
Explanation:
/^([[:blank:]]*[[:digit:]]+){2,3}[[:blank:]]*$/ - match only lines with 2 or 3 numbers.j = (NF==3) ? $2 : 1 - set variable j to $2 if there are 3 columns otherwise set j to 1for(i=$1; i<=$NF; i+=j) run a loop from 1st col to last col, increment by jsprintf is used for formatting the generated sequence 1 is default awk action to print each line