text processing (line break) in shell script

Question

I have the following file:

cat file1.m

(4 (5 y^7 (-1 + 4 z) + y^6 (15 - 83 z + 80 z^2) -
    5 z^4 (-2 + 4 z - 3 z^2 + z^3) + y^5 (-20 + 147 z - 273 z^2 + 140 z^3) +
    y z^3 (40 - 154 z + 147 z^2 - 83 z^3 + 20 z^4) +
    y^2 z^2 (60 - 254 z + 363 z^2 - 273 z^3 + 80 z^4) +
    y^3 z (40 - 254 z + 462 z^2 - 439 z^3 + 140 z^4) +
    y^4 (10 - 154 z + 363 z^2 - 439 z^3 + 160 z^4)) -
9 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3 + y^3 (-1 + 4 z) +
    y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, y) -
9 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3 + y^3 (-1 + 4 z) +
    y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, z) +
36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) +
    z^2 (6 - 5 z + 3 z^2)) H(1, z) +
36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) +
    z^2 (6 - 5 z + 3 z^2)) H(2, y))/(216 y z (-1 + y + z) (y + z)^4)

I want to rewrite this file so that all the leading spaces are removed and also I want to force after some column (say column 80) to break the line. So far the first problem is solved using

sed -e 's/^[ \t]*//' file1.m > file2.m

But how to break the line after some column? The desired output is

(4 (5 y^7 (-1 + 4 z) + y^6 (15 - 83 z + 80 z^2) - 5 z^4 (-2 + 4 z - 3 z^2 + z^3)
+ y^5 (-20 + 147 z - 273 z^2 + 140 z^3) + y z^3 (40 - 154 z + 147 z^2 - 83 z^3
+ 20 z^4) + y^2 z^2 (60 - 254 z + 363 z^2 - 273 z^3 + 80 z^4) + y^3 z (40
- 254 z + 462 z^2 - 439 z^3 + 140 z^4) + y^4 (10 - 154 z + 363 z^2 - 439 z^3
+ 160 z^4)) - 9 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3 + y^3 (-1
+ 4 z) + y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, y) - 9 (y + z)^4 (2 + y^2 (3 - 9 z)
- 4 z + 3 z^2 - z^3 + y^3 (-1 + 4 z) + y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, z)
+ 36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) + z^2 (6 - 5 z + 3 z^2))
H(1, z) + 36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) + z^2 (6 - 5 z
+ 3 z^2)) H(2, y))/(216 y z (-1 + y + z) (y + z)^4)

Nehal J Wani · Accepted Answer · 2016-08-14 15:09:12Z

4

You can use a combination of tr and fold:

$ sed 's/^[ \t]*//' a.m | tr -d '\n' | fold -w80
(4 (5 y^7 (-1 + 4 z) + y^6 (15 - 83 z + 80 z^2) -5 z^4 (-2 + 4 z - 3 z^2 + z^3) 
+ y^5 (-20 + 147 z - 273 z^2 + 140 z^3) +y z^3 (40 - 154 z + 147 z^2 - 83 z^3 + 
20 z^4) +y^2 z^2 (60 - 254 z + 363 z^2 - 273 z^3 + 80 z^4) +y^3 z (40 - 254 z + 
462 z^2 - 439 z^3 + 140 z^4) +y^4 (10 - 154 z + 363 z^2 - 439 z^3 + 160 z^4)) -9
 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3 + y^3 (-1 + 4 z) +y (-4 + 12 z
 - 9 z^2 + 4 z^3)) H(0, y) -9 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3 +
 y^3 (-1 + 4 z) +y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, z) +36 y z (-5 y^3 + 3 y^4 
+ y z^2 + y^2 (6 + z - 6 z^2) +z^2 (6 - 5 z + 3 z^2)) H(1, z) +36 y z (-5 y^3 + 
3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) +z^2 (6 - 5 z + 3 z^2)) H(2, y))/(216 y z (-
1 + y + z) (y + z)^4)

answered Aug 14, 2016 at 15:09

Nehal J Wani

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1 Comment

BabaYaga Over a year ago

Is it possible to start each line with a +/-?

Walter A · Accepted Answer · 2016-08-15 15:11:30Z

1

You can make your own folding rules using sed. Here is how you can make a + or - as the first character of your line.

sed -e 's/^[ \t]*//' file1.m | 
   tr -d '\n' | 
   sed 's/\(\(.\)\{,80\}\) \([\+\-]\)/\1\n\3/g'

EDIT: Without formatting the backslashes disappeared. I also removed the lowerbound of 70 in \{70,80\}. Result:

(4 (5 y^7 (-1 + 4 z) + y^6 (15 - 83 z + 80 z^2) - 5 z^4 (-2 + 4 z - 3 z^2
+ z^3)+ y^5 (-20 + 147 z - 273 z^2 + 140 z^3) + y z^3 (40 - 154 z + 147 z^2
- 83 z^3+ 20 z^4) + y^2 z^2 (60 - 254 z + 363 z^2 - 273 z^3 + 80 z^4)
+ y^3 z (40- 254 z + 462 z^2 - 439 z^3 + 140 z^4) + y^4 (10 - 154 z + 363 z^2
- 439 z^3+ 160 z^4)) - 9 (y + z)^4 (2 + y^2 (3 - 9 z) - 4 z + 3 z^2 - z^3
+ y^3 (-1+ 4 z) + y (-4 + 12 z - 9 z^2 + 4 z^3)) H(0, y) - 9 (y + z)^4 (2
+ y^2 (3 - 9 z)- 4 z + 3 z^2 - z^3 + y^3 (-1 + 4 z) + y (-4 + 12 z - 9 z^2
+ 4 z^3)) H(0, z)+ 36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2) + z^2 (6
- 5 z + 3 z^2))H(1, z) + 36 y z (-5 y^3 + 3 y^4 + y z^2 + y^2 (6 + z - 6 z^2)
+ z^2 (6 - 5 z+ 3 z^2)) H(2, y))/(216 y z (-1 + y + z) (y
+ z)^4)

edited Aug 15, 2016 at 15:11

answered Aug 14, 2016 at 17:50

Walter A

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3 Comments

BabaYaga Over a year ago

This solution would be great, but with the example that you have provided, its not working. Error: sed: 1: "s/((.){70,80}) ([+-])/\ ...": \1 not defined in the RE

Walter A Over a year ago

Fixed. I also added the result.

BabaYaga Over a year ago

Thanks a lot. It works perfectly in linux. Two minor issues : 1. It breaks the last line unnecessarily i.e. the + z)^4) part still remains within column 80 in the previous line. 2. It wont work on mac, probably because mac sed is different than unix sed. Anyway this is still great.

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