linux list cron jobs

a combination of multiple unit, the system starts is to start a number of unit,target is used to manage these unit.# Systemctl List-unit-files--type=target//View all target of current system# Systemctl List-dependencies multi-user.target//View a target contains all the unit, in a tree-shaped column.# Systemctl Get-default//view system default target# Systemctl Set-default multi-user.target//set default tar

UnitService System ServicesTarget multiple units consisting of groupsDevice hardware devicesMount File System mount pointAutoMount Automatic mount pointPath file or pathSCOP is not an external process initiated by SYSTEMDSlice Process GroupSnapshot Systemd SnapshotSocket inter-process communication socketsSwap fileTimer TimerUnit-related instructionsSystemctl List-units lists the running unitSystemctl list

method:Either write the absolute path or write your own command to the PATH environment variable in/etc/crontab, but the surest way is to write the absolute pathRecommendation: Each write a task plan, to append the correct log and error log, so as to be able to be documented, do not perform a task scheduled to view the task execution log can be wrong[Email protected] ~]# crontab-lNo crontab for Root[Email protected] ~]# CRONTAB-EEnter the following line in the task plan:1 2 /usr/bin/find/tmp/-t

storage location is/BACKUPS/ETC-YYYY-MM-DD3 * * 1-6/bin/cp/etc/backups/etc-$ (date+ '%y-%m-%d ')[[email protected] ~]# mkdir-p/backups/etc[[email protected] ~]# crontab e[[email protected] etc]# CRONTAB-L20 3 * * 1- 6/bin/cp/etc/backups/etc-$ (date + '%y-%m-%d ')Every Sunday 2:30 A.M., run the CP command to back up the/etc/fstab file with a storage location of/BACKUP/FSTAB-YYYY-MM-DD-HH-MM-SS2 * * 7/bin/cp/etc/fstab/backup/fstab-$ (date + '%y-%m-%d-%h-%m-%s ')[[email protected] etc]# mkdir-p/ba

The efficiency of the PHP dead loop to handle timed tasks is very low. It is recommended that you use the Linux built-in timer Task crontab command to invoke the PHP script to implement. This article is mainly to share with you the PHP combined with Linux cron command to implement timed task instances, I hope to help everyone. Two ways to schedule PHP tasks:1, t

order to ensure that the task is well documented.-l list, view the list of scheduled taskscrontab -lTask Scheduler cron files in /var/spool/cron/ directory, if Root cron is/ var/spool/cron/root (cat view)-R Delete Schedulecrontab

minute. Standard output (Stout): Code 1 using > or >> Standard error Output (STDERR): Code is 2 using 2> or 2>> Black Hole/dev/null Error Output 2>1 Cron lets scheduled tasks not output on screen using >/dev/null 2>1 [Root@wx-a ~]# Crontab-l*/1 * * * echo "Hello" >>/tmp/test.txt[Root@wx-a ~]# Cat/tmp/test.txtHello[Root@wx-a ~]# Cat/tmp/test.txtHelloHello Let the output go inside the black hole. [Root@wx-a ~]# Crontab-l*/1 * * * * echo "Hello"

Cron is a Daemon,cron job for Linux that is a task that Cron is scheduled to perform. Cron uses a special configuration file, the crontab file, to set the execution time or frequency of a command or script. Crontab has previously been introduced to the basics of use, no long

Purpose: because the server is running for a long time, it may cause some programs to occupy too much resources, so it requires a server reboot. Implementation method: Use the Cron service to view the Cron service status with service Crond State, or service Crond start if it is not started, A cron service is a timed service that can be added to or edited by the c

Connect to one of the Linux system scheduled tasks: at commandSystem in the daily operation, often need to make some cycle of backup or inspection work. This regular cycle of work tasks, in the Linux system is implemented with Crond system services. Crond is a daemon that is used to periodically perform certain tasks or wait for certain events under Linux, which

Linux Task Scheduler Cron[Email protected] ~]# CRONTAB-ENo crontab for root-using an empty oneThis is done 3 o'clock in the morning every day.0 3 * * */usr/bin/touch/root/123.txt >/dev/nullStart the service[Email protected] ~]# systemctl start CrondBasic format:* * * * * commandTime-sharing Weekly commandThe 1th column represents minutes 1~59 per minute with * or */1The 2nd column represents the hour 1~23 (

} ' "blacklist=$ (eval ${command})Block_ips ${blacklist}} function Check_all () {Tailnum=$1Retry=$2 Command= "Tail-n ${tailnum} ${logfile} |awk ' {print \$1} ' |sort |uniq-c ' (|awk > \$1}) {print ${retry} '"blacklist=$ (eval ${command})Block_ips ${blacklist}} Check_rootFor logfile in ${logfiles[@]}TodoCheck_post wp-login.php 10000 100Check_post wp-comments-post.php 10000 100Check_all 10000 1000Done To give the file editable permissions: chmod +x block_ips.shAdd automatic task, not 5 minute

I. Linux Task Scheduler cronThe operation of the Cron Task Scheduler function is done through the crontab command.Among the options that are commonly used are:-U: Specify a user, the no-u option is the current user;/etc/crontab a configuration file for a task planThe first two lines are defined variables, the third line refers to who sent the message, and then the last line has five points corresponding to

to receive notification messages for task execution results:normal results not received : COMMAND >/dev/nullall results are not received : COMMAND >/dev/null(2) for crontab file,% has a special function, if the command will appear in the%, remember to escape, or use single quotation marks to its reference;(3) Crontab's path variable is not exactly the same as the user's variable, so it is recommended that the task in cron use an absolute pathPractice

In linux, the name of the method for executing tasks with cron: crontab permission: all users use crontabfile [-uuser]-to replace the current crontab with the specified file. Crontab-[-uuser]-replace the current crontab with the standard input. crontab-1 [u... in linux, the name of the method for executing tasks with cron