0 Basic Learning Cloud computing and Big Data DBA cluster Architect "Linux Bash shell Programming and system Automation January 11, 2015 Monday"

Basic Commands1.SortSort by the first letter of ASCII-n Sort Ascending by number size-R Descending Sort-u reject duplicate rows-k-t together with-K to specify the column-T Specify delimiter2.UniqReject Duplicate Rows3.seqsequenceseq Ten-represents a number starting with 1 and listing up to 10 at 1 intervals.seq 2 Ten-represents a number starting with 2 and listing up to 10 at 1 intervals.seq 1 2 Ten-represents a number starting at 1, and a list of 10 before the 2 interval.seq Ten-1 1==================================Shell1. Role2. constituent elements1FileName.SH  2) The first line of the file #!/bin/Bash3) Body variable process Judgment Statement system command3. How to execute a script1) Bash script name2)./Script Name--you need to have executable permissions on the script==========variables1. Definition: Changeable value, can be called repeatedly, change the value continuously.2. How to set: variable name =assigned value.3. How to call the $ variable name4. Classification1) Local variables: Valid only for the current environment. 2Environment variable: valid for child shell. Set the way export variable name =value5. Clear the unset variable name6. Replace1) display number of Bits ${variable name: Number 1: Number 2}--Show starting from number one, number two represents several notes: counting starts from zero [email protected]~]# num=123456789[[Email protected]~]#Echo${num:1:6}234567   2) culling some start characters [[email protected]~]#Echo${file#/tmp}/a/b/c/d/e/f/Test3keep only the file name [email protected]~]#Echo${file##/*/}test 4) Change the file suffix name in volume [[email protected] ~]# echo ${file%}.sh/tmp/a/b/c/d/e/f/test.sh[[email protected] ~]# echo ${file%.txt}.sh7. Type variables use declare to declare variable types [[email protected] ~]# a=1[[email protected] ~]# b=2[[email  protected] ~]# c=a+b[[email protected] ~]# echo $a 1[[email protected] ~]# echo $b 2[[email  Protected] ~]# echo $ca +b[[email protected] ~]# declare-i a=1[[email protected] ~]# declare-i B=2[[email&nbsp  ;p rotected] ~]# declare-i c=a+b[[email protected] ~]# echo $C 3$ (()) represents an arithmetic expression, [[email protected] ~]# c=$ (($a + $b)) [[email protected] ~]# echo $c ==========================================1. Conditional Judgment Statement if condition-->condi tion refers to the condition of the judgment then CMD1--and CMD1 refers to the statement executed after satisfying the judgment condition else CMD2--CMD2 refers to the statement that does not meet the judgment condition execution Fiif C   Onditionthen cmd1elif conditionthen cmd2else cmd3firead can be used to assign keyboard input to a variable usage read variable name value READ-P "hint information" variable name 2.test judgment Man Test View related judgment instruction usage [] number judgment-gt greater than-ge greater than or equal to-LT  -le less than or equal to-ne is not equal to-eq equals the character's judgment-Z null = Word typeface, etc.! = Character not equal-n non-null logic with-a logic or-O file judgment-D file is not a directory-F is a plain file-E File is not present =======================for:1. Function: Loop statement usage for variable in value range do cmddonefor i in Test1 test2 {1..10} $ (seq   1) do cmddone command line mode: For I in {1..10};d o echo $i;d one===========================================while Loop statement usage while    Condition-to-meet condition executes the cmd do cmd donebash-x in debug mode to run the script to show the process of running the script until loop statement usage: until     Condition---condition does not satisfy the use of cmd do cmd donecase multiple conditional judgment Statement usage: Case value in value 1) CMD1;;     Value 2) CMD2;;     Value 3) CMD3;;        *) * represents all the above values, do some operations. CMD4;;         The esaccontinue action in the Loop statement represents a jump out of this loop into the next loop. Break acts in a loop statement to represent a direct jump out of the loop. Continue example: For I in {1..10}do  If [$i-eq 5] Then continue fi echo $idone [[[Email protected] tmp]# bash Example of continue.sh 1234678910break CExample of ontinue: For i in {1..10}do if [$i-eq 5] then break fi Echo $idone [[email protected] tmp]# bash break.sh 1234 think: Require output 100 below all can be divisible by 7, but can not be divisible by 5 number.

0 Basic Learning Cloud computing and Big Data DBA cluster Architect "Linux Bash shell Programming and system Automation January 11, 2015 Monday"