linux-stuff

linux-stuff

######### ubuntu linux #########
1) host file:
 
127.0.0.1	localhost
127.0.1.1       zhongkongliang-desktop
 
# The following lines are desirable for IPv6 capable hosts
::1     localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
 
2) bash:
  a) check exit code and exit. use if statement:
     if [ $? -ne 0 ]; then  ## notice the space between [ and $ .
       exit 1
     fi
 
3) display linux system info:  uname -a

4) E: Unmet dependencies:
   use:  sudo apt-get --purge autoremove -f to remove uncomplete packages or reinstall them.


### System Manage:
 
1) find where a pakage is installed:
    dpkg -l |grep name
    dpkg -s pkgName
 
2) query package: rpm -q <pkg-name>
 
3) install rpm pakage in ubuntu:
   try  rpm  -ivh  my-pkg.rpm  and get the following error msg:
   RPM should not be used directly install RPM packages, use Alien instead
   so:
   sudo apt-get install alien
   sudo alien my-pkg.rpm
   sudo -i my-pkg.deb
 
4) manage jobs:
   "Ctrl-z" : suspend running task
    jobs: list background jobs.
    fg: make background job running in frontground.  e.g. fg %1
    bg: background job.
    kill background job:  kill %1    , num 1 is the num in the jobs list.

5) search software: e.g.
   sudo apt-cache search jdk

   show package info: sudo apt-cache show pkg-name

################################


######## Mac OS: ########
1) install port:
  a) sudo port -d selfupdate
 
  install some pkgs using port:
  b) sudo port install iterm2
  c) sudo port install tree  // the tree command on linux.
  
 
2) use port to install emacs:
  $ sudo port install emacs
  Or, if you want the Aqua version:
  $ sudo port install emacs-app
  To keep it up to date:
  $ sudo port -u upgrade emacs
 
3) macos emacs:  esc+x = M-x
######################### 

############# Shell commands: ##############
1) unzip -l : list the contents of a zip archive. e.g.
      unzip -l maven-hello-world-portlet.zip 
   similar as: tar -tf  and  jar -tf
 
2) find exclude directory:
   find /path/to/dest -type d \( ! -name tmp \) -o \( ! -name cache -prune \) -print  ## The -prune option make sure that you do not descend into directory
 
3) delete all directories under curr-directory except ROOT :
   find .  -maxdepth 1 -type d \( ! -name "ROOT" \) -print0 | xargs -0 rm -rf
 
4) sudo sh : get root shell.

5) replace one char in filename for all matched files:
   find . -name "*-*" -exec bash -c 'mv "$1" "${1//-/_}"' _ {} \;
   ## replace word in file name:
   find . -name "*.html" -exec bash -c 'mv "$1" "${1//html/scala.html}"' _ {} \;   
 
6) delete all .svn directories recursively:
   find . -type d -name ".svn" exec rm -rf {} \;

7) execute a line of commands with one sudo: sudo sh -c  ??
   e.g.  sudo sh -c "echo 2 >> /data/zookeeper/myid"

8) count occurrences of a char in a text file:
   fgrep -o <xxx> <file> |wc -l

### locale:
can not write and view chinese character in terminal. locale -l, not find zh_CN.UTF-8

1) sudo locale-gen zh_CN.UTF-8
2) echo "export LC_ALL=zh_CN.UTF-8" >> ~/.bashrc
3) restart terminal
4) use LC_ALL=C.UTF-8 can work too. but LC_ALL=C will not work.

key point: if locale -l not have zh_CN.UTF-8, then generate one.

upgrade ubuntu failed:
run these commands in terminal:
sudo apt-get update
sudo apt-get upgrade

find . -type f -print0 | "xargs" -0 -e grep -nH -e

-- show linux version: 
   uname -a

-- show distribution info:
   lsb_release -a

-- count disk usage in curr dir:
   du -hs .

-- find a command on shell:
   --> which cmd
   --> alias -p | grep cmd

### PROCESS SUPERVISION:
1) via supervisord :
   supervisorctl

   supervisord will auto load all *.conf file in /etc/supervisor/conf.d/*.conf
   (configured in /etc/supervisor/supervisord.conf, see the files section)

   supervisor conf example:
      [program:nodehook]
      command=/usr/bin/node /srv/http.js
      directory=/srv
      autostart=true
      autorestart=true
      startretries=3
      stderr_logfile=/var/log/webhook/nodehook.err.log
      stdout_logfile=/var/log/webhook/nodehook.out.log
      user=root
      environment=SECRET_PASSPHRASE='this is secret',SECRET_TWO='another secret'

   run: sudo supervisorctl update to load new conf file.

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