在逗號之後創建換行符 - 在所需的行寬之前

在像這樣的文件中：

ruler    1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890
\usage{
function(
parameter,
parameterparameter,
parameter = parameter,
parameter = p,
parameter = para,
parameter = para,
paramete = p,
parameterparameter = pa,
parameter = p,
p = pa,
param,
parameterpara = par,
paramet = par,
parameter = param,
parameterpa = param,
...
more lines

我想將帶有“usage”的行連接到帶有“…”的行，然後在第 80 個字元（列）之前的逗號之後創建新的換行符。

現在，我設法在第 n 個逗號之後換行，但它效率不高，因為在許多情況下，在第 3 個逗號之後會留下很多空格。所以我希望換行符前的逗號盡可能接近第 80 個字元。

sed -i -r '/usage/{:a;N;/\.\.\./!ba;s/\n//g}' filename.txt
sed -i 's/\(\([^,]\+,\)\{3\}\)/\1\n/g;s/\n/\n/g' filename.txt

我查看了“par”、“fold”和“fmt”文件，但沒有成功。“折疊”接近但在空格中分割行而不是逗號：

sed -i -r '/usage/{:a;N;/\.\.\./!ba;s/\n//g}' filename.txt
fold -s filename.txt | tee filename.txt

一個惰性變體，使用perl’s slurp 模式：

perl -0777 -pi -e '
 s{\\usage.*?\n\.\.\.\n}{
   ($r = $&) =~ s/\n//g;
   $r =~ s/\G.{0,79}(,|.$)\K/\n/g;
   $r
 }gse' your-file

這使：

        1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890
\usage{function(parameter,parameterparameter,parameter = parameter,
parameter = p,parameter = para,parameter = para,paramete = p,
parameterparameter = pa,parameter = p,p = pa,param,parameterpara = par,
paramet = par,parameter = param,parameterpa = param,...
more lines

使用awk：

$ awk '/^\\usage/,/^\.\.\./ { if (length(line $0) >= 80) { print line; line = $0 } else line = line $0; next  }; line != "" { print line; line = "" }; 1' file
        1         2         3         4         5         6         7         8
12345678901234567890123456789012345678901234567890123456789012345678901234567890
\usage{function(parameter,parameterparameter,parameter = parameter,
parameter = p,parameter = para,parameter = para,paramete = p,
parameterparameter = pa,parameter = p,p = pa,param,parameterpara = par,
paramet = par,parameter = param,parameterpa = param,...
more lines

程式碼，awk註釋：

/^\\usage/,/^\.\.\./ {
       # This block triggers for all lines between a line
       # starting with "\usage" and another line
       # starting with "..."

       # If our saved output line and the current line together
       # is longer or equal to 80 characters, print the output
       # line and reset it to the current line.  Else, add the
       # current line to the end of the saved output line.
       if (length(line $0) >= 80) {
               print line
               line = $0
       } else
               line = line $0

       # Skip to next line of input.
       next
}

# If we get here and the saved output line is
# non-empty, then there is data to output, so
# do that.
line != "" { print line; line = "" }

# Print all input.
1

引用自：https://unix.stackexchange.com/questions/579416