5 ways to calculate string lengths in shell scripts and get a line from text

Sometimes in the Linux operating system need to calculate the length of a string, through the query data to collate the current shell to get the length of the string of several methods, here to share, the method is as follows:

Method 1: Use the wc-l command
Wc-l can get the length of the current row, so the string for a single row can be obtained in this simple way, and the wc-l is the number of rows that get the current string content.

The code is as follows: Echo "ABC" |wc-l

Method 2:expr Length string
Use expr length to get the lengths of a string

Method 3:awk Gets the number of fields, but if there is a problem when the length is greater than 10 characters, you need to confirm later

The code is as follows: Echo "abc" |awk-f "" ' {print NF} '

Method 4: Get the string length by awk+length

The code looks like this: echo "Alex" |awk ' {print length ($)} '

Method 5: Via Echo ${#string} (Note: String here is the variable name of the string)

The code is as follows: Name=alex
echo ${#name} 1, print the first column of the file (domain): awk ' {print '} ' filename
2. Print the first two columns of the file (domain): awk ' {print $1,$2} ' filename
3. Print out the first column, then print the second column: awk ' {print $ {$} ' filename
4. Total number of printed text files: awk ' end{print NR} ' filename
5. Print the first line of text: awk ' nr==1{print} ' filename
6. Print the second line of text the first column: Sed-n "2, 1p" filename | awk ' print ' awk-f ', ' END {print $ ' BIRoomTime20160229.txt

There are two kinds of assignment methods in the shell, in the form
1) arg= ' (command) '
2) arg=$ (command)
Therefore, if you want to assign the total number of rows of a file to the variable nlines, it can be expressed as:
1) nlines= ' (awk ' end{print NR} ' filename) '
Or
2) nlines=$ (awk ' end{print NR} ' filename)

5 ways to calculate string lengths in shell scripts and get a line from text