Script: only converts long rows.

Script: only change a long row. For example, scan a file quickly to see which rows are too long: 1awk '{if (length ($0)> 72) another interesting method of {print $0} 'filename is to use the $ # vamname structure in shell. It returns the length of any variable that replaces vamname (content, not a variable name ). 01 #! /Bin/sh02 03 # toolong. sh -- use fmt. sh to format long lines that exceed the specified length 04 05 width = 7206 07if [! -R "$1"]; then08 echo "Usage: 'basename $ 0' filename "> & 209 exit 110fi11 12 while read input13do14 if [$ {# input}-gt $ width]; then15 echo" $ input "| fmt. sh16 else17 echo "$ input" 18 fi19done <$120 21 exit 0 is an interesting method to process input files. First, use a simple <$1 to achieve the purpose of the input file, and then use a read input to parse each line. If your shell environment does not have the $ {# var} notation, you can use the following method instead: 1 varlength = "$ (echo" $ var "| wc-c) "However, the wc command has a very annoying feature, and its output has a leading space to make the output list more beautiful. To avoid this annoying problem, there will be a slight change, that is, when the last pipe is passed, only the number is allowed through: [NOTE: In my Linux, I have not found this feature mentioned by the author and may be faulty when sed is used, you need to test] 1 varlength = "$ (echo" $ var "| wc-c | sed's/[^: digit:] // ') in your own environment. "Running result: 01 $ toolong ragged.txt 02So she sat on, with closed eyes, and half believed herself in03Wonderland, though she knew she had but to open them again, and04all wocould change to dull reality -- the grass wocould be only rustling05in the wind, and the pool rippling to the waving of the reeds -- the06rattling teacups wocould change to tinkling sheep-bells, and the07Queen's shrill cries to the voice of the shepherd boy -- and the08sneeze09of the baby, the shriek of the Gryphon, and all the other queer10noises, wocould change (she knew) to the confused clamor of the busy11farm-yard -- while the lowing of the cattle in the distance would12take the place of the Mock Turtle's heavy sobs.13 14 Notice that, unlike a standard invocation of fmt, toolong has retained line breaks where possible, so the word "sneeze," 15 which is on a line by itself in the input file, is also on a line by itself in the output.