mjhjmtu

I am trying to replace every instance of a block of six rows with another block of six rows, just reducing the six rows block of two columns to a six rows block of only one column.

Thank you to your comments I'll write this question more clearly. I have several guitar tablature text files each with many "lines" of music. Each "line" of music has 6 (as the guitar number of strings) consecutive rows of text. Between the "lines" of music there are empty (or with some text) lines. Normally these six row "lines" are about two hundred columns length, and I want to reduce the length of the lines by replacing each six vertical row of -- by a six vertical row of -.

As an example. I would like to reduce the first chunk to the second.

|------------------| |-------| 
|------------------| |-------| 
|-0----------------| |-0-----| 
|-2-----2-----2----| |-2-2-2-| 
|-------2----------| |---2---| 
|-------------0----| |-----0-| 

I have tried the following code (seen on unix.stackexchange 1) without success:

sed -i '/--/,/--/,/--/,/--/,/--/,/--/c
-
-
-
-
-
-' a.txt

I have had no better results with awk or vim or perl.

A partial solution, for example using awk with Field Separator empy, would be: find two consecutive columns all whose characters are either empty or "-". Then delete one of the two columns. But I do not know how to do it.

The tablature you posted seems to be built on six-character long pieces, -x----, where x is either a fret number or a dash. Like so:

 123456123456123456
 -x-----x-----x----
|------------------|
|------------------|
|-0----------------|
|-2-----2-----2----|
|-------2----------|
|-------------0----|

If they're all with that spacing, you can just simply change the pieces to remove some dashes, without regard for other lines.

$ sed -Ee 's/-(.)----/-1/g; s/|/-|/2' < tab
|-------| 
|-------|
|-0-----|
|-2-2-2-|
|---2---|
|-----0-|

But if you have tabs written with different spacings in the same file, then it gets much harder, as we'd need to recognize the spacing for each tab, and in general, that can't even be done from the first line. (since it can be empty as in your example.)

The solutions I can come up with for the more general case involve decoding the whole tablature and then reprinting it and that won't fit in this answer.

Note that sed's /this/,/that/ syntax processes blocks of lines where the first line matches /this/, the last line matches /that/, and the block contains all lines in between. /--/,/--/,/--/,... is therefore nonsense, since there are more patterns than just the start and end of a block.

To match a block that looks like a tablature, you'd need to match the |- and then have the block extend for six lines. In GNU sed, you could use /^|-/,+6 for that.

I have done by below method

command

i=`awk 'print NR' l.txt | sort -nr | sed -n '1p'`

 for ((j=1;j<=$i;j++)); do sed -n ''$j'p' filename|awk -F "" 'gsub("","n",$0);print $0'|sort | uniq;done| sed '/^$/d'| sed "N;s/n/ /g"| awk 'print $NF,$1'| sed -r "s/ //g"

output

x
x
x
x
x
x