（5） Printf (instead of echo)

#!/bin/bash
# printf  from  POSIX  Standard definition , Therefore use  printf  The script is better than using  echo  Good portability 
# (1)  Use reference text and spaces to separate parameters 
# (2)  Can be found in printf Using format string ,  You can set the string width 、 The odd way of left and right 
# (3)  Default printf I don't want to echo Automatically add line breaks , have access to  \n
# (4)  grammar ： printf format-string [arguments...]
# format-string: Format control string 
# arguments: parameter list 

printf "%-10s %-8s %-4s\n"  full name   Gender   weight kg
printf "%-10s %-8s %-4.2f\n"  Zhang San aaaaaaaaaaaaaaaaaaaaaa  Woman  55.5555
printf "%-10s %-8s %-4.2f\n"  Li Si   male  66.5775
printf "%-10s %-8s %-4.2f\n"  Wang Wu   Woman  55.1234
# %s: Output a string 
# %c: Output a character 
# %d: Output an integer 
# %f: Output a decimal 
# %-10s: A width of 10 Character string （- Indicates left alignment , There is no right alignment ）, Not enough space to fill , Show all of more 
# %-4.2f: It means to format it as a decimal , among  .2  Finger retention 2 Decimal place .

printf '%d %s\n' 1 "2"
printf '%d %s\n' "1" '2'
# printf %d %s 1 2 #error

#  Escape character 
:<<EOF
\a	 Warning characters , Usually it is ASCII Of BEL character 
\b	 back off 
\c	 Inhibition （ No display ） Any ending newline characters in the output result （ Only in %b Valid in parameter string under format indicator control ）, and , Any character left in the parameter 、 Any subsequent parameters and any characters left in the format string , All ignored 
\f	 Change the page （formfeed）
\n	 Line break 
\r	 enter （Carriage return）
\t	 Horizontal tabs 
\v	 Vertical tabs 
\\	 A literal backslash character 
\ddd	 Express 1 To 3 The character of a digit octal value . Valid only in format string 
\0ddd	 Express 1 To 3 The octal character of a bit 
EOF