195. Tenth Line
For example, assume that file.txt has the following content:
Line 1
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9
Line 10
Your script should output the tenth line, which is:
Line 10
answer：sed -n '10p' file.txt
192. Word Frequency
Write a bash script to calculate the frequency of each word in a text file words.txt.
For simplicity sake, you may assume:
words.txt contains only lowercase characters and space ' ' characters.
Each word must consist of lowercase characters only.
Words are separated by one or more whitespace characters.
For example, assume that words.txt has the following content:
the day is sunny the the
the sunny is is
Your script should output the following, sorted by descending frequency:
the 4
is 3
sunny 2
day 1
answer:cat words.txt | tr -s "\t| " "\n" | sort |uniq -c |sort -k 1 -r|awk '{print $2,$1}'
194. Transpose File
Given a text file file.txt, transpose its content.
You may assume that each row has the same number of columns and each field is separated by the ' ' character.
For example, if file.txt has the following content:
name age
alice 21
ryan 30
Output the following:
name alice ryan
age 21 30
answer:awk '{for(i=1;i<=NF;i++) if(NR==1) a[i]=$i;else a[i]=(a[i]" "$i);} END{for (i in a) print a[i];}' file.txt #这个解非原创
193. Valid Phone Numbers
Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.
You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)
You may also assume each line in the text file must not contain leading or trailing white spaces.
For example, assume that file.txt has the following content:
987-123-4567
123 456 7890
(123) 456-7890
Your script should output the following valid phone numbers:
987-123-4567
(123) 456-7890
answer:grep '^[0-9]\{3\}-[0-9]\{3\}-[0-9]\{4\}$\|^([0-9]\{3\})\s[0-9]\{3\}-[0-9]\{4\}$' file.txt
ps:{}需要进行转义\{\} ;()不需要转义;空格\s
