Cmds¶
Add User¶
$ sudo adduser <username>
Delete a User¶
$ sudo deluser <username>
$ sudo userdel <username>
If, instead, you want to delete the user’s home directory when the user is deleted, you can issue the following command as root:
$ sudo deluser --remove-home <username>
$ sudo deluser -r <username>
$ sudo userdel -r <username>
Changing User Password¶
$ sudo passwd <username>
Allowing other users to run sudo¶
$ sudo adduser <username> sudo
$ sudo visudo
# $ vim /etc/sudoers
# User privilege specification
root ALL=(ALL:ALL) ALL
or ALL=(ALL:ALL) ALL
# Allow members of group sudo to execute any command
%sudo ALL=(ALL:ALL) ALL
http://askubuntu.com/questions/7477/how-can-i-add-a-new-user-as-sudoer-using-the-command-line
https://help.ubuntu.com/community/RootSudo#Allowing_other_users_to_run_sudo
Delete a user from one group¶
$ groupdel group
Remove sudo privileges from a user (without deleting the user)¶
$ sudo deluser username sudo
Users and Groups name list¶
getent passwd | awk -F':' '{ print $1}'
getent passwd | awk -F: '{print $1}' | while read name; do groups $name; done
kuser (KDE User Manager)
apt-file search¶
ERROR: cmake/modules/FindKDE4Internal.cmake not found in
apt-file search FindKDE4Internal.cmake
kdelibs5-dev: /usr/share/kde4/apps/cmake/modules/FindKDE4Internal.cmake
mtu¶
ifconfig eth0 mtu 1400 # 1360, 1406 or 1407 , default is 1500
dpkg-reconfigure¶
dpkg-reconfigure kdm
dpkg-reconfigure gdm
rfkill¶
# ifconfig wlan0 up
SIOCSIFFLAGS: Operation not possible due to RF-kill
# rfkill list
0: phy0: Wireless LAN
Soft blocked: yes
Hard blocked: no
# rfkill unblock 0
# rfkill list
0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
# ifconfig wlan0 up
Run wireshark with capture packets privilege¶
http://wiki.wireshark.org/CaptureSetup/CapturePrivileges
setcap 'CAP_NET_RAW+eip CAP_NET_ADMIN+eip' /usr/bin/dumpcap
groupadd wireshark
usermod -a -G wireshark omidraha
chgrp wireshark /usr/bin/dumpcap
chmod 4750 /usr/bin/dumpcap
dpkg-reconfigure wireshark-common
┌────────────────────────────────────────────────────────────────┤ Configuring wireshark-common ├─────────────────────────────────────────────────────────────────┐
│ │
│ Dumpcap can be installed in a way that allows members of the "wireshark" system group to capture packets. This is recommended over the alternative of running │
│ Wireshark/Tshark directly as root, because less of the code will run with elevated privileges. │
│ │
│ For more detailed information please see /usr/share/doc/wireshark-common/README.Debian. │
│ │
│ Enabling this feature may be a security risk, so it is disabled by default. If in doubt, it is suggested to leave it disabled. │
│ │
│ Should non-superusers be able to capture packets? │
│ │
│ <Yes> <No> │
│ │
└─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
Install, Remove, Purge and get Info of Packages¶
To install package
dpkg -i package-file-name
To remove (uninstall) package
dpkg -r package-file-name
To Purge package
dpkg -P package-file-name
To get info of package
dpkg -l | grep 'package-file-name'
Create A Local Debian Mirror With apt-mirror¶
http://www.howtoforge.com/local_debian_ubuntu_mirror
apt-get install apt-mirror
vim /etc/apt/mirror.list
set base_path /mnt/sdc1/OR/apt-mirror
# set mirror_path $base_path/mirror
# set skel_path $base_path/skel
# set var_path $base_path/var
# set cleanscript $var_path/clean.sh
# set defaultarch <running host architecture>
# set postmirror_script $var_path/postmirror.sh
# set run_postmirror 0
set nthreads 20
set _tilde 0
deb http://172.16.1.210/repo/debian testing main contrib non-free # 32 bit
deb-amd64 http://172.16.1.210/repo/debian testing main contrib non-free # 64 bit
# set cleanscript $var_path/clean.sh
clean http://172.16.1.210/repo/debian
su - apt-mirror -c apt-mirror
/mnt/sdc1/OR/apt-mirror/var/clean.sh
Named pipe¶
In computing, a named pipe (also known as a FIFO for its behavior) is an extension to the traditional pipe concept on Unix and Unix-like systems, and is one of the methods of inter-process communication (IPC).
The concept is also found in Microsoft Windows, although the semantics differ substantially.
A traditional pipe is “unnamed” because it exists anonymously and persists only for as long as the process is running.
A named pipe is system-persistent and exists beyond the life of the process and must be deleted once it is no longer being used.
Processes generally attach to the named pipes (usually appearing as a file) to perform inter-process communication.
Instead of a conventional, unnamed, shell pipeline, a named pipeline makes use of the filesystem.
It is explicitly created using mkfifo() or mknod(), and two separate processes can access the pipe by name, one process can open it as a reader, and the other as a writer.
mkfifo /tmp/testfifo
tail -f /tmp/testfifo
and in another console:
echo HELLO! > /tmp/testfifo
Give Privilege to a non-root process to bind to ports under 1024¶
setcap 'cap_net_bind_service=+ep' $(readlink -f `which python`)
How do I test whether a number is prime?¶
http://www.madboa.com/geek/openssl/#prime-test
$ openssl prime 119054759245460753
1A6F7AC39A53511 is not prime
You can also pass hex numbers directly.
$ openssl prime -hex 2f
2F is prime
Download from YouTube¶
https://github.com/rg3/youtube-dl
# apt-get install youtube-dl
$ youtube-dl https://www.youtube.com/watch?v=video_id --proxy http://host:port
$ youtube-dl -v -i --no-mtime --no-check-certificate --youtube-skip-dash-manifest https://www.youtube.com/watch?v=video_id
How to use youtube-dl from a python program¶
url = raw_input('URL:')
dl = youtube_dl.YoutubeDL({'outtmpl': u'%(id)s.mp4',
'forceduration': True,
'restrictfilenames': True,
'format': '18/22/5',
'writesubtitles': True})
res = dl.extract_info(url)
duration = res['duration']
title = res['title']
vid = res['id']
ext = res['ext']
web_page_url = res['webpage_url']
subtitles = entry['subtitles']
Youtube options:
Download Youtube videos with Youtube subtitles on¶
# To download sub
$ youtube-dl --no-mtime --proxy http://127.0.0.1:8080 -f 18 --write-sub URL
# To embed sub
$ youtube-dl --no-mtime --proxy http://127.0.0.1:8080 -f 18 --embed-subs URL
Redirect output to null¶
$ echo 123 >/dev/null 2>&1
cron¶
You do not have to restart cron every time you make a change because cron always checks for changes, But to restart cron whenever you made change:
$ sudo service crond restart
In Ubuntu:
$ sudo service cron status
$ sudo service cron restart
Display the current crontab:
$ crontab -l
Edit the current crontab:
$ crontab -e
Syntax of crontab (field description)
* * * * * /path/to/command arg1 arg2
* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)
How do I use operators?
An operator allows you to specifying multiple values in a field. There are three operators:
The asterisk (*):
This operator specifies all possible values for a field. For example, an asterisk in the hour time field would be equivalent to every hour or an asterisk in the month field would be equivalent to every month.
The comma (,):
This operator specifies a list of values, for example: “1,5,10,15,20, 25”.
The dash (-):
This operator specifies a range of values, for example: “5-15” days , which is equivalent to typing “5,6,7,8,9,….,13,14,15” using the comma operator.
The separator (/):
This operator specifies a step value, for example: “0-23/” can be used in the hours field to specify command execution every other hour. Steps are also permitted after an asterisk, so if you want to say every two hours, just use */2.
Resources:
Generate random base64 characters¶
$ openssl rand -base64 741
Set Socket Buffer Sizes¶
# sysctl -w net.core.rmem_max=2096304
# sysctl -w net.core.wmem_max=2096304
Ping¶
-s packetsize
Specifies the number of data bytes to be sent. The default is 56, which translates into 64 ICMP data bytes when combined with the 8 bytes (in my local system, 28 bytes) of ICMP header data.
-M pmtudisc_opt
Select Path MTU Discovery strategy. pmtudisc_option may be either do (prohibit fragmentation, even local one), want (do PMTU discovery, fragment locally when packet size is large), or dont (do not set DF flag).
# ping -c 1 -M do -s 1472 google.com
PING google.com (173.194.113.167) 1472(1500) bytes of data.
1480 bytes from www.google.com (173.194.113.167): icmp_seq=1 ttl=42 time=262 ms
--- google.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 262.920/262.920/262.920/0.000 m
Change owner of directory¶
$ chown -R or:or .
Locate/print block device attributes¶
# blkid
/dev/sda6: UUID="2fc31bf0-68f1-4566-975b-cb995277db10" TYPE="swap"
/dev/sda1: UUID="ec3c1569-29bb-4a63-bd75-337c57c7b600" TYPE="ext4"
Create a new UUID value¶
$ uuidgen
d2ad5b28-b306-4096-aca2-dd66c37da5af
SSH¶
# socks5 proxy with dynamic tcp/ip
$ ssh -D 8080 user@remote_host
$ ssh -L 8080:localhost:80 user@remote_host
# connect to remote running program on the remote host, for example TinyProxy
$ ssh -N user@remote_host -L 8080:localhost:8888
Force ssh client to use only password authentication¶
ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no user@remote_host
Secure copy¶
$ scp -r Prj username@remote_ip:/directory/path/in/remote/ip/
Install SSH server and SSH client¶
$ sudo apt-get install openssh-server
$ sudo apt-get install openssh-client
Create a new ssh key¶
$ ssh-keygen -t rsa -C "mail@example.com"
Generating public/private rsa key pair.
Enter file in which to save the key (/home/or/.ssh/id_rsa): /home/or/.ssh/bitbucket_rsa
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/or/.ssh/bitbucket_rsa.
Your public key has been saved in /home/or/.ssh/bitbucket_rsa.pub.
$ ssh-add ~/.ssh/bitbucket_rsa
$ vim ~/.ssh/config
IdentityFile ~/.ssh/bitbucket_rsa
$ chmod 400 ~/.ssh/bitbucket_rsa
SSH connection with public key¶
$ vim ~/.ssh/authorized_keys
# add public key
Disable the Password for Root Login¶
$ sudo vim /etc/ssh/sshd_config
PasswordAuthentication no
$ sudo /etc/init.d/ssh restart
Youtube download trick¶
$ youtube-dl --no-mtime --verbose -i 'ytsearch100:table tennis training' --get-title
$ youtube-dl --no-mtime --verbose -i 'ytsearch100:table tennis training'
Run process as background and never die¶
$ nohup node server.js > /dev/null 2>&1 &
$ ./run.py > /dev/null 2>&1 &
nohup means: Do not terminate this process even when the stty is cut off.
> /dev/null means: stdout goes to /dev/null (which is a dummy device that does not record any output).
2>&1 means: stderr also goes to the stdout (which is already redirected to /dev/null).
& at the end means: run this command as a background task.
Eject CD/DVD-ROM¶
eject - eject removable media
$ eject
$ eject -t
- -t
With this option the drive is given a CD-ROM tray close command. Not all devices support this command.
Search for a package¶
$ apt-cache search package_name
Un mount cd-rom device that is busy error¶
# umount /cdrom
# fuser -km /cdrom
# umount -l /mnt
Login with linux FTP username and password¶
$ ftp ftp://username:password@my.domain.com
Download torrent¶
$ aria2c download.torrent
Debug SSH¶
# ssh -vT root@127.0.0.1
Detect ssh authentication types available¶
ssh -o PreferredAuthentications=none 127.0.0.1
Permission denied (publickey,password).
ssh -o PreferredAuthentications=none 127.0.0.2
Permission denied (publickey).
ssh -o PreferredAuthentications=none 127.0.0.3
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Avoid SSH’s host verification for known hosts?¶
ssh -o "StrictHostKeyChecking no" 127.0.0.1
http://superuser.com/questions/125324/how-can-i-avoid-sshs-host-verification-for-known-hosts
Set environment variables on linux¶
$ export PATH=${PATH}:/home/or/bin
Base64 decode encode¶
or@debian:~$ echo 'Test' | base64
VGVzdAo=
or@debian:~$ echo 'Test' | base64 | base64 -d
Test
Extract compressed files¶
# Decompressed a file that is created using gzip command.
# File is restored to their original form using this command.
$ gzip -d mydata.doc.gz
$ gunzip mydata.doc.gz
# Decompressed a file that is created using bzip2 command.
# File is restored to their original form using this command.
$ bzip2 -d mydata.doc.bz2
$ gunzip mydata.doc.bz2
# Extract compressed files in a ZIP archive.
$ unzip file.zip
$ unzip data.zip resume.doc
# Untar or decompressed a file(s) that is created using tar compressing through gzip and bzip2 filter
$ tar -zxvf data.tgz
$ tar -zxvf pics.tar.gz *.jpg
$ tar -jxvf data.tbz2
# Extract tar files and to another directory
$ tar -xvf archive.tar -C /target/directory
# List files from a GZIP archive
$ gzip -l mydata.doc.gz
# List files from a ZIP archive
$ unzip -l mydata.zip
# List files from a TAR archive
$ tar -ztvf pics.tar.gz
$ tar -jtvf data.tbz2
# To unzip a file that is only compressed with bz2 use
$ bunzip2 filename.bz2
# To unzip things that are compressed with .tar.bz2 use
$ tar -xvjpf filename.tar.bz2
# To unzip things that are compressed with .gz use
$ gunzip file.doc.gz
# Don't store full absolute paths in the archive
# This will archive `/home/or/ws/data` directory without absolute path to the `data.tar` file
$ tar -cf data.tar -C /home/or/ws/ data
Options for tar files:
Type at the command prompt
tar xvzf file-1.0.tar.gz – to uncompress a gzip tar file (.tgz or .tar.gz) tar xvjf file-1.0.tar.bz2 – to uncompress a bzip2 tar file (.tbz or .tar.bz2) tar xvf file-1.0.tar – to uncompressed tar file (.tar)
x = eXtract, this indicated an extraction c = create to create ) v = verbose (optional) the files with relative locations will be displayed. z = gzip-ped; j = bzip2-zipped f = from/to file … (what is next after the f is the archive file)
The files will be extracted in the current folder. HINT: if you know that a file has to be in a certain folder, move to that folder first. Then download, then uncompress – all in the correct folder. Yes, I’m lazy.. no I don’t like to copy files between directories, and then delete others to clean up. Download them in the correct directory and save yourself 2 jobs.
List All Environment Variables¶
$ env
$ printenv
$ printenv | less
$ printenv | more
Set Environment variable¶
$ export MY_VAR="my_val"
Set proxy in command line¶
$ export http_proxy="http://127.0.0.1:8080"
$ export https_proxy="https://127.0.0.1:8080"
$ export ftp_proxy="http://127.0.0.1:8080"
How can I tunnel all of my network traffic through SSH?¶
http://superuser.com/questions/62303/how-can-i-tunnel-all-of-my-network-traffic-through-ssh
$ sudo sshuttle --dns -vvr username@remote_ip.121 0/0
How can you completely remove a package?¶
http://askubuntu.com/questions/151941/how-can-you-completely-remove-a-package
$ sudo apt-get purge package_name
This does not remove packages that were installed as dependencies, when you installed the package you’re now removing.
Assuming those packages aren’t dependencies of any other packages,
and that you haven’t marked them as manually installed,
you can remove the dependencies with:
$ sudo apt-get autoremove
or (if you want to delete their systemwide configuration files too):
$ sudo apt-get --purge autoremove
How to forward X over SSH from Ubuntu machine …¶
http://unix.stackexchange.com/questions/12755/how-to-forward-x-over-ssh-from-ubuntu-machine
X11 forwarding needs to be enabled on both the client side and the server side.
On the client side, the -X (capital X) option to ssh enables X11 forwarding,
and you can make this the default (for all connections or for a specific conection)
with ForwardX11 yes in ~/.ssh/config.
On the server side, edit the /etc/ssh/sshd_config file, and uncomment the following line:
X11Forwarding Yes
The xauth program must be installed on the server side.
$ aptitude install xauth
After making this change, you will need to restart the SSH server. To do this on most UNIX’s, run:
$ /etc/init.d/sshd restart
To confirm that ssh is forwarding X11,
Check for a line containing Requesting X11 forwarding in the output:
$ ssh -v -X USER@SERVER
Note that the server won’t reply either way.
SOCKS server and/or client¶
http://www.delegate.org/delegate/SOCKS/
http://ajitabhpandey.info/2011/03/delegate-a-multi-platform-multi-purpose-proxy-server/
Download delegate from http://delegate.hpcc.jp/anonftp/DeleGate/bin/linux/latest/ and extract it.
Then run binary file as:
Run a Http proxy that is connected to a socks:
$ ./dg9_9_13 -P8080 SERVER=http SOCKS=127.0.0.1:9150 ADMIN="local@localhost.com"
$ youtube-dl -v --proxy "http://127.0.0.1:8080" https://www.youtube.com/watch?v=VID
SSH hangs on debug1: expecting SSH2_MSG_KEX_ECDH_REPLY¶
Edit /etc/ssh/ssh_config, uncomment the following lines
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc
GSSAPIAuthentication yes
GSSAPIDelegateCredentials no
MACs hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160
Add the following line:
HostKeyAlgorithms ssh-rsa,ssh-dss
Also change MTU may be useful:
ifconfig eth0 mtu 578
What will this command do?¶
$ exec 2>&1
The 1 number refer to stdout, and The 2 number refer to stderr
it duplicates, or copies, stderr onto stdout.
When you run a program, you’ll get the normal output in stdout, but any errors or warnings usually go to stderr.
If you want to pipe all output to a file for example, it’s useful to first combine stderr with stdout with 2>&1
http://stackoverflow.com/questions/1216922/sh-command-exec-21
http://www.catonmat.net/blog/bash-one-liners-explained-part-three/
Sample guake script¶
$ vim /home/or/workspace/bin/start.guake.sh
guake -r "OR";
guake -n New_Tab -r "root"; -e "su";
guake -n New_Tab -r "Ipython 2" -e "ipython";
guake -n New_Tab -r "workspace" -e "cd /home/or/workspace/;clear;";
guake -n New_Tab -r "prj" -e "cd /home/or/workspace/prj/;clear;";
guake -n New_Tab -r "dg" -e "cd /home/or/workspace/Tools/dg/dg9_9_13/DGROOT/bin/;clear;";
$ chmod +x vim /home/or/workspace/bin/start.guake.sh
Verify that apt is pulling from the right repository¶
$ apt-cache policy <Packge-Name>
Example:
$ apt-cache policy docker-engine
Output:
Installed: 1.9.1-0~stretch Candidate: 1.9.1-0~stretch Version table: *** 1.9.1-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 100 /var/lib/dpkg/status 1.9.0-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.8.3-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.8.2-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.8.1-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.8.0-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.7.1-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.7.0-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.6.2-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.6.1-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.6.0-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages 1.5.0-0~stretch 500 500 https://apt.dockerproject.org/repo debian-stretch/main amd64 Packages
Operation not permitted on file with root access¶
# ls -la /etc/resolv.conf
-r--r--r-- 1 root root 56 Jan 7 22:39 /etc/resolv.conf
# chmod u+rwx /etc/resolv.conf
chmod: changing permissions of ‘/etc/resolv.conf’: Operation not permitted
# lsattr /etc/resolv.conf
----i--------e-- /etc/resolv.conf
# chattr -i /etc/resolv.conf
# lsattr /etc/resolv.conf
-------------e-- /etc/resolv.conf
rsync and sudo over SSH¶
Add the line <username> ALL=NOPASSWD:<path to rsync>,
where username is the login name of the user that rsync will use to log on.
That user must be able to use sudo
- Note:
Put the line after all other lines in the sudoers file! I first added the line after other user configurations, but it only worked when placed as absolutely last line in file on lubuntu 14.04.1.
$ sudo visudo
<username> ALL=NOPASSWD:<path to rsync>
Example:
$ which rsync
/usr/bin/rsync
$ sudo visudo
ubuntu ALL=NOPASSWD:/usr/bin/rsync
How to backup with rsync¶
$ rsync -avz -e ssh --rsync-path="sudo rsync" <username>@<remote_host>:/path/on/remote/host/to/backup /path/on/local/host/to/save/backup
Using rsync for local backups
$ rsync -av --delete /Directory1/ /Directory2/
- -a
recursive (recurse into directories), links (copy symlinks as symlinks), perms (preserve permissions), times (preserve modification times), group (preserve group), owner (preserve owner), preserve device files, and preserve special files.
- -v
verbose. The reason I think verbose is important is so you can see exactly what rsync is backing up. Think about this: What if your hard drive is going bad, and starts deleting files without your knowledge, then you run your rsync script and it pushes those changes to your backups, thereby deleting all instances of a file that you did not want to get rid of?
- –delete
This tells rsync to delete any files that are in
Directory2that aren’t inDirectory1. If you choose to use this option, I recommend also using the verbose options, for reasons mentioned above.
Full Daily Backup with Syncing Hourly Backup by rsync and cron¶
$ crontab -e
0 */2 * * * hourly_sync_backup.sh
0 */8 * * * daily_full_archive_backup.sh
$ service cron restart
$ vim hourly_sync_backup.sh
rsync -avz -e ssh --rsync-path="sudo rsync" <username>@<remote_host>:/path/on/remote/host/to/backup /path/on/local/host/to/save/hourly_sync_backup
$ vim daily_full_archive_backup.sh
rsync -avz -e ssh --rsync-path="sudo rsync" <username>@<remote_host>:/path/on/remote/host/to/backup /path/on/local/host/to/save/daily_full_archive_backup
tar -P -cvjf /path/on/local/host/to/save/archives/daily_full_archive_backup_$(date +%Y_%m_%d).tar.bz2 /path/on/local/host/to/save/daily_full_archive_backup
Backup with rsync works but not in crontab¶
$ rsync -avze "ssh -i ~/.ssh/my_key" ...
http://www.howtogeek.com/135533/how-to-use-rsync-to-backup-your-data-on-linux/?PageSpeed=noscript
https://www.marksanborn.net/howto/use-rsync-for-daily-weekly-and-full-monthly-backups/
Sample ssh config file¶
$ vim ~/.ssh/config
Host <alias-host-name>
HostName <IP>
User <username>
IdentityFile ~/.ssh/<host>_key
Host gb
HostName github.com
User omidraha
IdentityFile ~/.ssh/github_key
$ ssh gb
Compress directory¶
$ tar -zcvf archive-name.tar.gz directory-name
Where:
-z : Compress archive using gzip program
-c: Create archive
-v: Verbose i.e display progress while creating archive
-f: Archive File name
http://www.cyberciti.biz/faq/how-do-i-compress-a-whole-linux-or-unix-directory/
How to add path of a program to $PATH environment variable?¶
Edit .bashrc in your home directory and add the following line:
$ vim ~/.bashrc
export PATH="/path/to/dir:$PATH"
$ source ~/.bashrc
Could not open a connection to your authentication agent¶
$ eval `ssh-agent -s`
How do I make ls show file sizes in megabytes?¶
$ ls -l --block-size=M
$ ls -lh
How to check one file exist on specific path ?¶
#!/usr/bin/env bash
if test -f /path/to/some/file; then
echo "File exist"
fi
Or to check file dose not exist:
#!/usr/bin/env bash
if test ! -f /path/to/some/file; then
echo "File not exist"
fi
what does echo $$, $? $# mean ?¶
$ echo $$, $$, $#, $*
$$ is the PID of the current process.
$? is the return code of the last executed command.
$# is the number of arguments in $*
$* is the list of arguments passed to the current process
http://www.unix.com/shell-programming-and-scripting/75297-what-does-echo-mean.html
Make ZSH the default shell¶
chsh -s $(which zsh)
ulimit¶
The ulimit and sysctl programs allow to limit system-wide resource use.
This can help a lot in system administration, e.g. when a user starts too many processes and therefore makes the system unresponsive for other users.
$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 63619
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 65536
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 63619
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
$ sudo sysctl -a
www.linuxhowtos.org/Tips and Tricks/ulimit.htm
locate¶
$ sudo apt-get install mlocate
$ updatedb
$ locate some-resource-name
Posting Form Data with cURL¶
Start your cURL command with curl -X POST and then add -F for every field=value you want to add to the POST:
$ curl -X POST -F 'username=or' -F 'password=pass' http://domain.tld/post
Diff¶
Eskil is a graphical tool to view the differences between files and directories
http://eskil.tcl.tk/index.html/doc/trunk/htdocs/download.html
Telegram¶
Telegramm-cli
resolve_username tabletennis
Convert Socks into an HTTP proxy¶
By using pproxy:
$ sudo pip install pproxy[accelerated
$ pproxy -l http://0.0.0.0:8118 -r socks5://0.0.0.0:9150 -vvvvv
By using polipo (Deprecated):
$ sudo apt-get install polipo
$ sudo service polipo stop
$ sudo vim /etc/polipo/config
logSyslog = true
logFile = /var/log/polipo/polipo.log
# HTTP Proxy
proxyAddress = "0.0.0.0"
proxyPort=8080
# Socks Proxy
socksParentProxy = "127.0.0.1:9150"
socksProxyType = socks5
chunkHighMark = 50331648
objectHighMark = 16384
serverMaxSlots = 64
serverSlots = 16
serverSlots1 = 32
$ sudo service polipo restart
How to use sshuttle¶
$ sshuttle -r username@sshserver 0.0.0.0/0
locale.Error: unsupported locale setting¶
$ export LC_ALL="en_US.UTF-8"
$ export LC_CTYPE="en_US.UTF-8"
$ sudo dpkg-reconfigure locales
Shadowsocks¶
$ sudo pip install shadowsocks
$ sudo ssserver -c ~/ws/shadowproxy.json --user nobody -d start
V2ray¶
$ sudo bash <(curl -L https://raw.githubusercontent.com/v2fly/fhs-install-v2ray/master/install-release.sh)
$ v2ray run --config=s.json
$ v2ray run --config=c.json
Capture and recording screen¶
$ sudo apt-get install byzanz
$ byzanz-record -d 60 record.gif
Inotify Watches Limit¶
$ vim /etc/sysctl.conf
fs.inotify.max_user_watches = 524288
$ sudo sysctl -p --system
https://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit
Monitor multiple remote log files with MultiTail¶
$ sudo apt-get install multitail
# example for two log-files
$ multitail log-file_a log-file_b
# example for two log-files and two columns
$ multitail -s 2 log-file_a log-file_a
# example for two log-files and different colors
$ multitail -ci green log-file_a -ci yellow -I log-file_a
# example for one log file on remote
$ multitail -l "ssh -t <user>@<host> tail -f log-file"
# example for two log files on remote
$ multitail -l "ssh -l <user>@<host> tail -f log-file_a" -l "ssh -l <user>@<host> tail -f log-file_b"
Register GPG key by curl instead of dirmngr¶
$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys D6BC243565B2087BC3F897C9277A7293F59E4889
Error traceback:
Executing: /tmp/apt-key-gpghome.voccUPwlky/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys D6BC243565B2087BC3F897C9277A7293F59E4889
gpg: connecting dirmngr at '/run/user/0/gnupg/d.k4bafrtss9g1d86f8y5rxb8h/S.dirmngr' failed: IPC connect call failed
gpg: keyserver receive failed: No dirmngr
Note that add 0x prefix before the 5523BAEEB01FA116 key
$ curl -sL "http://keyserver.ubuntu.com/pks/lookup?op=get&search=0x5523BAEEB01FA116" | sudo apt-key add
Install fonts¶
$ sudo apt-get install font-manager
$ font-manager
Install tzdata noninteractive¶
$ apt-get install -y tzdata
$ ln -fs /usr/share/zoneinfo/Asia/Tehran /etc/localtime
$ dpkg-reconfigure --frontend noninteractive tzdata
If you are fine with UTC:
$ DEBIAN_FRONTEND=noninteractive apt-get install -y tzdata
Inotify Watches Limit¶
Error:
External file changes sync slow: The current inotify limit is too low
Fixed:
$ vim /etc/sysctl.conf
fs.inotify.max_user_watches = 524288
$ sudo sysctl -p --system
https://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit
The following packages will be upgraded¶
- The following packages will be upgraded:
grub-efi-amd64-bin grub-efi-amd64-signed shim-signed
$ sudo apt-get install <list of packages kept back>
$ sudo apt-get update ; sudo apt-get dist-upgrade
Restart¶
journalctl --list-boots
grep reboot /home/*/.bash_history
grep reboot /root/.bash_history
history | grep -i reboot
history | grep -i init
last reboot
Install jq¶
sudo apt-get install jq