1. interactive input
interactive interface [read]
：read a b c
aa bb cc
The read command may define a plurality of variables simultaneously; and the contents of the input space as a separator in default, the value input to the corresponding variable; If the default value is excessive, the final value will be all assigned to the last variable; if the default too little, extra variable or a null
How to read input:
echo "Please enter a directory:" // we need to cancel echo -n number newline
Example: echo "Please enter a directory:"; read variables
Please enter a directory: / etc
Common parameters:
-p read -p "Enter a directory:" variable
-t timeout defined read -t 5 -p "Please enter a directory:" variable
The default value script
Typing -------------------------------
| |
Input is not entered correctly ----- ------------
| | | |
Correct Incorrect, input must be given to Tip defaults
[ ! -n $filename ]
Exercise: Enter basic information about a device file, the output of this device file
. 1 ! # / Bin / the bash 2 . 3 # . 4 . 5 Read -t . 5 - P "Enter a device file name:" devname . 6 . 7 [$ devname the -Z] = `devname && && Exit the fdisk -l` . 1 . 8 . 9 10 . 11 iF [-b / dev / $ devname]; the then # - B whether the block file 12 is 13 is the fdisk -l / dev / $ devname 14 15 Exit 0 16 . 17 the else 18 is . 19 echo "$ devname device file is not" 20 is 21 is echo " Usage: 'Please enter a device file, such as: sda' " 22 23 exit 2 24 25 fi
2. for loop
case statement
The syntax of the case statement:
Variables in case
patten1）
Block 1
；；
patten2）
Block 2
；；
*）
esac
for scenarios statement:
There is a function, this function needs to execute the cycle, but different execution object; the object must be the same [Data]
format for statement:
a = [ 'a', 'b', 'c'] - the python program, in many cases we need to call the appropriate methods to generate a list;
for variable in list; do
Loop
done
Exercise: 99 multiplication table
1 #!/bin/bash 2 3 for I in`seq 9`;do 4 5 for j in `seq 9`;do 6 7 [$j -le $i] && echo -n -e “$i*$j=`echo $(($i*$j))`\t” 8 9 done 10 11 echo “ ” 12 13 done
. 1 ! # / Bin / the bash 2 . 3 # multiplication table . 4 . 5 for I in { . 1 .. . 9 }; do . 6 . 7 for J in $ I; do . 8 . 9 echo -n -e "* $ I $ J = $ [$ I * $ J] \ T " 10 . 11 DONE 12 is 13 is echo 14 15 DONE
echo -e
-e make echo command, a special symbol can be identified
\ R carriage return line feed is not
\ N newline
\ T tab spaces tab = 4
unix2dos \ r \ n \ n
dos2unix
List Builder way:
1. Direct given string list
for i in a b c d e;do
Loop
done
2. The list of integers
a {start ... end} //{1..1} == python is not acceptable in the range {1..9}
b seq command reference $ (seq [start [step]] end)
Step python range {1,100,2}
seq 20 30
Title: implemented for this loop through the host network segment about up
1 declare -I sum=0 2 3 for i in $(seq 1 254);do 4 5 ping -c 1 -w 1 10.6.12.$i &> /dev/null 6 7 if [ $? -eq 0 ];then 8 9 let sum++ 10 11 echo ”10.6.12.$i是通的” 12 13 else 14 15 echo " 10.6 . 12 is . $ I is illogical" 16 . 17 Fi 18 is . 19 DONE 20 is 21 is echo "$ sum total of online computer"
3. Return the command list
$(COMMAND)
Scenarios: ls / var / log /
Title: Analyzing all files / var / log / a. A file ending in .log statistical processing and display:
. 1 ! # / Bin / the bash 2 . 3 # . 4 . 5 DECLARE -i SUM = 0 . 6 . 7 for I in $ ( LS / var / log /); do . 8 . 9 IF [ "* .log" = $ I]; the then 10 . 11 echo $ I 12 is 13 is the let SUM ++ 14 15 Fi 16 . 17 DONE 18 is . 19 echo "ending with a file .log: $ SUM "
4. glob mechanisms - mechanisms file name wildcards
$ (Ls / var / log /)
/ Var / log / *
test command summary:
The option -a -o 1.test commands can only be used in the command
例如【`du -h $filename|cut -d: -f1` -lt 100k -a -x $filename】
test `du -h $filename |cut -d: -f1` -lt 100k -a -x $filename
Note: when doing string matching, and does not support regular wildcard
2.test test==[[]]
And then connect the two test commands, you can not use the internal command option -o -a
General use || && ==! => = <=
For example: [. [Yum.log == * log]]
5. variable references
$ @ $ * As the parameter list for the cycle
$ 0 - and not the same as awk
$ 0 for the bash script file to run
[Executive] awk awk row in the entire line $ 0
Need more time to use the word "$ @" requires a word when using "$ *"