Use awk to process tagged text

When using awk to process tagged text, assume there is a string like "123 <em> abc </em> 456 <em> def </em> 789 <em> ghi </em> "the string in the question, to intercept the length of 5, the returned string should be 123ab. to intercept the length of 8, 123 <em> abc </em> 45 should be returned. Appendix: 1 <em> and </em> labels cannot be counted within the length. 2. The original <em> tag must be retained for the truncated string. However, if the last tag is not closed, the start tag is removed. Code: as follows #! /Bin/basha = '2014 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'echo "test text is' $ a' "read-p" please input a number little than 'echo $ a | awk' {gsub ("<em >|</em> ", "", $0); printf length ($0 )}'': "num echo $ a | awk-vnum =" $ num "-vFS = '</em>'' {for (I = 1; I <= NF; I ++) {orisum = sum; sum + = length ($ I)-4; if (sum <= num) {strlist = strlist ~ /./? Strlist "" FS "" $ I: $ I} else {sub ("<em>", "", $ I); strlist = strlist ~ /./? Strlist "" FS "" substr ($ I, 1, num-orisum): substr ($ I, 1, num-orisum); break} print strlist} 'Test Result: [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 212 [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 5123ab [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 7123 <em> abc </em> 4 [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 10123 <em> abc </em> 456d [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 9123 <em> abc </em> 456 [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 14123 <em> abc </em> 456 <em> def </em> 78 [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 17123 <em> abc </em> 456 <em> def </em> 789gh [root @ localhost ~] # Bash 1.sh test text is '2017 <em> abc </em> 123 <em> def </em> 456 <em> ghi </em> 'Please input a number little than 18: 18123 <em> abc </em> 456 <em> def </em> 789 <em> ghi </em> [root @ localhost ~] #