Logrotate failed because parent directory has insecure permissions (It's world writable or writable by group which is not "root")

 

Error:

error: skipping "output.log" because parent directory has insecure permissions (It's world writable or writable by group which is not "root") Set "su" directive in config file to tell logrotate which user/group should be used for rotation.



Googled: Set "su" directive in config file to tell logrotate which user/group should be used for rotation.

Reference URL: https://www.suse.com/support/kb/doc/?id=000017263

su user group

in logrotate config file

/var/log/tomcat5/base/*.txt {
    su tomcat tomcat
    notifempty
    copytruncate
    weekly
    rotate 52
    compress
    missingok
}

/var/log/tomcat5/base/catalina.out {
    su tomcat tomcat
    notifempty
    copytruncate
    weekly
    rotate 52
    compress
    missingok
}

Systemctl add new service.

 

Reference URL: https://blog.thenets.org/how-to-create-a-service-for-fedora-rhel/

Create the background service file

[Unit] Description=my-service nginx example # You may want to start after your network is ready After=network-online.target Wants=network-online.target [Service] ExecStart=/usr/bin/env docker run --name nginx --rm -p 8080:80 docker.io/nginx:alpine Restart=Always PIDFile=/tmp/my_service_pid [Install] WantedBy=network-online.target

How to create a systemd service

# Create the service file vim /etc/systemd/system/my-service.service # (if you change an existent file, you must reload the daemon config) # Reload daemon config systemctl daemon-reload # Enable systemctl enable my-service.service # Start systemctl start my-service.service # (if you need to restart) # Restart systemctl restart my-service.service

multi-user.target.wants

Reference URL: https://www.tecmint.com/create-new-service-units-in-systemd/

/etc/systemd/system/multi-user.target.wants/

You can see some link files of unit services and some directories of the “wants” of a target. For example, what the multi-user target wants to be loaded when the boot procedure reaches its level, is listed in the directory with name /etc/systemd/system/multi-user.target.wants/.

As you can see it doesn’t contain only services but also other targets which are also collections of services.

Let’s make a service unit with the name connection.service.

# vim connection.service

and type the following (hit “i” for insert mode), save it, and exit (with “esc” and “:wq!” ) :

[Unit]
Description = making network connection up
After = network.target

[Service]
ExecStart = /root/scripts/conup.sh

[Install]
WantedBy = multi-user.target

Regex to split htop details

 

^( *\d+) (\w+) +(\d+) +(-?\d+) +(\d+.?\d?\w?) +(\w+) +(\w+) +S +(\d+.?\d+) +(\d+.?\d+) +(\d+h?:?\d?\d?:?\.?\d?\d?) +[├│└][\+─ ] (.*)$

gzip with -9 option

 
A log file: with size of: 789M

gzip with different option, to have different compression as below

gzip -9 file.log

32M

gzip -9 file.log

37MB

example #2

-rw-r--r--. 1 srvusr srvusr  87M Jul 18 19:53 output.log.20220718_pm074234.log

-rw-r--r--. 1 root   root    87M Jul 21 12:01 output.log.20220718_pm074234.without9.log

sudo gzip -9 output.log.20220718_pm074234.log

sudo gzip output.log.20220718_pm074234.without9.log

-rw-r--r--. 1 srvusr srvusr 4.0M Jul 18 19:53 output.log.20220718_pm074234.log.gz

-rw-r--r--. 1 root   root   4.2M Jul 21 12:01 output.log.20220718_pm074234.without9.log.gz

Sequence of 2>&1 in sh start script cause exceptions were not log into file, but show on screen.

Content of Hello.java

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        System.out.println("Hello");
        throw new Exception("world");
    }
}

-------------------------------------------------------------------------------------------------------

[billson@virtual-jenkins Documents]$ javac Hello.java; java -cp . Hello 2>&1 > null.txt
Exception in thread "main" java.lang.Exception: world
    at Hello.main(Hello.java:8)

[billson@virtual-jenkins Documents]$ cat null.txt
Hello

-------------------------------------------------------------------------------------------------------

[billson@virtual-jenkins Documents]$ javac Hello.java; java -cp . Hello > null 2>&1

[billson@virtual-jenkins Documents]$ cat null.txt

Hello
Exception in thread "main" java.lang.Exception: world
    at Hello.main(Hello.java:8)

Centos add user sudoers list

1. Create more users

Eg:

sudo useradd weiyang

sudo passwd weiyang

With this user will be able to run sudo:

sudo usermod -aG wheel weiyang

[billson@169 home]$ groups weiyang

weiyang : weiyang wheel

Reference URL: https://www.digitalocean.com/community/tutorials/how-to-create-a-sudo-user-on-centos-quickstart

How to display number of items in sub-directories from command line

Reference URL:
https://askubuntu.com/questions/1150749/how-to-display-number-of-items-in-sub-directories-from-command-line/1150753#1150753

Here's a little shell function that you can use. Just add these lines to your ~/.bashrc:

lsc(){
    ## globs that don't match should expand to a null string
  shopt -s nullglob
  ## If no arguments were given use the current dir
  if [[ $# -eq 0 ]]; then
    targets="."
  ## Otherwise, use whatever was given
  else
    targets=($@)
  fi
  ## iterate over the arguments given
  for target in "${targets[@]}"; do
    ## get the contents of the target
    contents=("$target"/*)
    ## iterate over the contents
    for thing in "${contents[@]}";  do
      ## If this one is a directory
      if [[ -d "$thing" ]]; then
        ## collect the directory's contents
        count=("$thing"/*)
        ## Print the dir's name (with a '/' at the end)
        ## and the number of items found in it
        printf "%s/ (%s)\n" "$thing" "${#count[@]}"
      else
        ## If this isn't a dir, just print the name
        printf "%s\n" "$thing"
      fi
    done
  done
}

then open a new terminal and run:

lsc /path/to/dir

For example, given the following directory (the \012 are newlines in the names):

crontab job report error/command not found, only error at schedule, not in manual execute sh script.

Reference URL: https://stackoverflow.com/questions/8127433/unable-to-run-a-service-command-via-cron






sbin is not in the path when run via cron. Specify the full path to service. This is probably either /sbin/service or /usr/sbin/service. You can find the path on your system by running which service.

Work around:

add " 2>&1" behind your crontab for those scripts you totally no idea how to handle "properly" in short time.

ps -ef grep -v multi

Google'ed by: ps -ef grep -v multi




Reference URL: https://stackoverflow.com/a/13330924/676104

Use a separated list of of processes:

#!/bin/bash
PROC="nginx mysql ..."
for p in $PROC
do
  ps cax | grep $p > /dev/null

  if [ $? -eq 0 ]; then
    echo "Process $p is running."
  else
    echo "Process $p is not running."
  fi

done

If you simply want to see if either one of them is running, then you don't need loo. Just give the list to grep:

ps cax | grep -E "Nginx|mysql|etc" > /dev/null

To exclude by using:


ps -ef | grep -vE "grep|vim |tail " | grep tomcat

Most common init systems for CentOS/others.

Reference URL: https://www.digitalocean.com/community/tutorials/how-to-configure-a-linux-service-to-start-automatically-after-a-crash-or-reboot-part-1-practical-examples


PostedAugust 19, 2015

• System V is the older init system:
  • Debian 6 and earlier
  • Ubuntu 9.04 and earlier
  • CentOS 5 and earlier
• Upstart:
  • Ubuntu 9.10 to Ubuntu 14.10, including Ubuntu 14.04
  • CentOS 6
• systemd is the init system for the most recent distributions featured here:
  • Debian 7 and Debian 8
  • Ubuntu 15.04 and newer
  • CentOS 7

WinSCP configure hostkey in winscp script

What's WinSCP hostkey


Before OpenSSH 6.8

 ssh-keygen -lf <(ssh-keyscan localhost 2>/dev/null)

Since OpenSSH 6.8, you have to add the -E md5 switch to get the format needed for WinSCP.

ssh-keygen -E md5 -lf <(ssh-keyscan localhost 2>/dev/null)

[billson@169 ~]$ ssh-keygen -E md5 -lf <(ssh-keyscan localhost 2>/dev/null)
2048 MD5:aa:bb:cc:xx:xx:xx:xx:43:79:ae:90:ca:83:d3:xx:ef localhost (RSA)
256 MD5:xx:81:xx:7a:xx:49:68:87:xx:a3:54:xx:61:b3:xx:15 localhost (ECDSA)
256 MD5:xx:69:29:4a:xx:f0:8f:74:xx:5d:1b:86:aa:xx:d7:1b localhost (ED25519)

USING (RSA)
GET CONTENT BETTWEN [MD5:]*********************[localhost (RSA)] without space
SUPPOSE also using 2048


Replace

open sftp://user:password@example.com/ -hostkey="ssh-rsa 2048 xx:xx:xx:xx:xx:xx:xx:xx..."

to:

open sftp://user:password@example.com/ -hostkey="ssh-rsa 2048 aa:bb:cc:xx:xx:xx:xx:43:79:ae:90:ca:83:d3:xx:ef"