Shell

first time blogging to share some recent work imagenet Introduction Imagenet is currently the world's largest image recognition of the database, the database contains a large number of image information, and these images have a basic tag information,

From the "Linnux program design," the second chapter, from one by one to knock out, the conclusion is that a few s did not come out effect #。 /bin/sh and #. There's a difference,/bin/bash. The first direct typing is the former, always output some-E,

When you extract or filter text from a file or command output, you can use regular expressions (R E), which are collections of special or not very special string patterns. ^ matches only the beginning of the line$ only match end of line* Only one

There are several main ways to do this: echo "$str" |awk ' {print length ($)} 'Expr Length "$str"echo "$str" |wc-cBut the third one will be 1 more, maybe the terminator is counted.There are three ways to determine that a string is empty:If ["$str" =

1. Write at the beginning Recently in the study Bang Bang shell, in the process of debugging encountered reverse debugging, is very distressed, and every debugging will be interrupted, a friend sent a post "1" introduced one of the Anti-tune, after

Hbase is a distributed, column-oriented, open-source database that is built on Google's bigtable theory and based on the Hadoop HDFs file system. HBase differs from a generic relational database (RDBMS).      is a database that is suitable for

In shell programming, it is often necessary to divide a string separated by a particular delimiter into an array, and in most cases we first think of using awkHowever, it is more convenient to actually use the shell's own split array function. IfA= "

forwarding https://my.oschina.net/weiqingbin/blog/190929 You can set the following options when you start Impala-shell to modify the command execution environment. Note: These options are different from the configuration options for the Impalad

Usage:ps [Options] Basic options:-A,-e all processes-a all with TTY, except Sessio N leaders a all with TTY, including and users-d all except session leaders-n, --deselect Negate selection R only running processes T all processes on this Terminal

You can't write this in Sh/bash, and if the Else branch doesn't have a statement execution, don't write this else.If ElseifIf statement syntax format:If conditionThenCommand1Command2...CommandNFiWrite a line (for the terminal command prompt):If [$

Through the shell script to configure the password-free login, divided into two scripts, one is the configuration file config.env, one is the formal script sshkey.sh.# config.envExport host_user=(root) export PASSWD=(a) export ssh_host= (192.168. 16

Tips Summary:String comparison with double brackets [[]]; arithmetic comparison with single brackets []--left and right spacesArithmetic operations with double parentheses (()); Shell commands and output parentheses ()--left and right without

#!/usr/bin/env BashFor year in/root/downloads/data/all/*DoEcho-ne ' basename $year. gz ' "\ T"Gunzip-c $year | \awk ' {temp = substr ($ 88, 5) + 0;Q = substr ($ 93, 1);if (temp! = 9999 && q ~/[01459]/&& temp > max) max = temp}END {print Max} 'Done#!/

1, there are two common ways to run a shell script:First give executable permission, then enter the directory where the file is located, enter:./name.sh;Run the interpreter and execute the script:/bin/sh name.sh, in which case there can be no #! in

If statement1, according to the file type to judge-d file) to determine if the file exists and is a character device file (the character device is true)-e file) to determine if the file exists (exists as true)[-e/root]echo $? The output is 0 #判断为真,

Functions: Code snippets that implement standalone functionalityfunction is only executed when calledSyntax One:function f_name{function body}Syntax Two:F_name () {function body}The return value of the function:Default function return value:

Shell Multi-Process basics Code block: With {} as a whole & function: Put the command in the background processing, idle out the current console for other operations Wait command: Waits for the parent process to execute the

13 Basic IF statementsFormat 1:if condition; Then statement; FiExecution result is 5Format 2:if condition; Then statement; else statement; Fi#!/bin/basha=5if [ $a -gt 10 ];then echo $aelse echo 0fiExecution result is 0Format 3:if ...; Then ...; Elif

Prerequisite: Configure your own machine ssh password-free login#!/bin/bashCat list1234EODWhile Read lineDoif SSH [email protected] "test-f/tmp/a.sh"; Then #配置了免密登录, no password is entered hereecho "$line file exist."Elseecho "$line file not exist."

Shellgawkgawk Options -f Specifies the field delimiter for delimited data fields in a row -f Specifies the handler's script name -V Var=value defining variables in the Gawk program -MF N Specifies the maximum number of rows to