bash cheat sheet

Debian specific

apt-get update
apt-get install software-properties-common
add-apt-repository ppa:certbot/certbot
apt-get update
apt-get install python-certbot-nginx
certbot --nginx #  for nginx

find packages that contain a certain file (e. g. a header file that is needed by a build)
```
apt-file search file_name
```

install VNC

apt-get update
apt-get install -y x11vnc
apt-get install gnome-core
x11vnc -storepasswd
apt install xinit
startx &
x11vnc -xkb -noxrecord -forever -noxfixes -noxdamage -display :0 -auth /var/run/lightdm/root/:0 -usepw &

install mount support for SMB protocol
```
apt install cifs-utils
```

temporary mount

mount //server/share /mnt/share -o user=user,pass=pass

persistent mount
edit /etc/fstab to persistently mount an SMB network share

  mkdir /media/yourshare
  id # note uid and gid, e. g. 1000 and 1004
  vi /etc/fstab

Password inside fstab Secure password outside fstab

Password inside fstab	Secure password outside fstab
fstab `servername/yourshare /media/yourshare cifs username=user,password=pass,uid=1000,gid=1004 0 0` `mount -a # reload fstab`	fstab `//server/share /pathto/mountpoint cifs credentials=/home/username/.smbcredentials,uid=shareuser,gid=sharegroup 0 0` Create the .smbcredentials file in your home directory: ~/.smbcredentials `username=shareuser password=sharepassword domain=domain_or_workgroupname` Make sure you secure your ~/.smbcredentials file: `chmod 0600 ~/.smbcredentials`

fstab

servername/yourshare      /media/yourshare      cifs    username=user,password=pass,uid=1000,gid=1004   0       0

mount -a # reload fstab

fstab

 //server/share /pathto/mountpoint cifs credentials=/home/username/.smbcredentials,uid=shareuser,gid=sharegroup 0 0

Create the .smbcredentials file in your home directory:

~/.smbcredentials

username=shareuser
password=sharepassword
domain=domain_or_workgroupname

Make sure you secure your ~/.smbcredentials file:

chmod 0600 ~/.smbcredentials

unmount persistent network share

vi /etc/fstab # remove entry from /etc/fstab
mount -a # reload fstab
umount /media/yourshare
rm /media/yourshare

update Debian

apt-get update # fetches the list of updates
apt-get upgrade # strictly upgrades the current packages
apt-get dist-upgrade # installs updates (new ones)

start programs automatically
```
crontab -e
```
```
@reboot command_or_script
```

send a mail

ssmtp recipent@domain.org
Subject: your subject
Text of mail

(then send mail with controlZ)

share folders over NFS

install mount support for NFS protocol
```
apt-get install nfs-common
```

edit fstab to persistently mount an NFS network share

mkdir /media/yourshare
vi /etc/fstab

/etc/fstab

servername:/yourshare    /media/yourshare   nfs     rsize=8192,wsize=8192,timeo=14,intr     0       0

mount -a # reload fstab

Mac specific

install gcc and make CMake use it instead of /usr/bin/g++ (i. e. XCode Clang)
```
brew install gcc
export CC=/usr/local/Cellar/gcc/9.1.0/bin/gcc-9
export CXX=/usr/local/Cellar/gcc/9.1.0/bin/g++-9
```
Adapt above path so it matches the one printed by brew info gcc.
print version of shared library
```
otool -L libName.dylib
```
share a file
```
sharing -a file_name
```
list files including extended attributes
```
ls -l@
```
show the names and values of all extended attributes of a file
```
xattr -l file
```
compress directory into zip archive
```
zip -r folder.zip /path/to/folder
```
compress directory into zip archive with password
```
zip -er folder.zip /path/to/folder
```
copy file content into clipboard
```
pbcopy < /path/to/source_file
```
copy clipboard content into file
```
pbpaste > /path/to/target_file
```

create directory hardlink

brew install hardlink-osx
hln /path/to/source_directory /path/to/target_directory

open file with associated app
```
open file_name
```
see the list of outdated software
```
softwareupdate --list
```
update all outdated software
```
softwareupdate --install --all
```
update specfic software
```
softwareupdate --install product_name
```

suspend system

/System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend

stop dock icons from bouncing

defaults write com.apple.dock no-bouncing -bool TRUE
killall Dock

Linux and Mac

create patch file

diff -u modified_file original_file >my_patch.patch

apply patch file

patch -u file_to_be_modified my_patch.patch

change text encoding of file (here from utf-16 to utf-8)

iconv -f utf-16 -t utf-8 </path/to/source_file >/path/to/target_file

print hex dump of file
```
xxd filename
```
print all environment variables
```
printenv
```
compare folder contents
```
diff -rq <folder1> <folder2>
```
print folder size
```
du -sh /path/to/folder
```

copy file to server

scp -P <port> local_file user_name@server_name:/target/path

ssh-login to server
```
ssh -l user_name -p <port> server_name
```

create symlink (example in /usr/local/bin)

ln -s /path/to/my_executable /usr/local/bin/my_executable

try to make PDF file smaller

gs -sDEVICE=pdfwrite -dNOPAUSE -dQUIET -dBATCH -dPDFSETTINGS=/PSL2Printer -dCompatibilityLevel=1.4 -sOutputFile=out.pdf in.pdf

list possible pdfsettings

gs -dNODISPLAY  -c ".distillersettings {exch ==only ( ) print ==} forall quit"

check which nfs shares are available on an nfs server
```
showmount -e server_name
```
list all files in a directory
```
find . -type f -ls
```
list all symlinks
```
find . -type l -ls
```
delete all files in a directory
```
find . -type f -delete
```
list currently running processes
```
top
```
find a process by its name
```
pgrep process_name
```
kill a process by its name
```
pkill process_name
```
create SSH key
```
ssh-keygen
```

switch on SSH logging

vi /etc/ssh/sshd_config # comment in LogLevel INFO
service ssh restart
tail -f /var/log/auth.log

change SSH port

vi /etc/ssh/sshd_config # change the line containing the port
service ssh restart

show processes that lock a file:
```
lsof /path/to/locked/file
```
change owner of a file
```
chown username filename
```

list files containing given text

list file names

grep -rl --include "*.ext" "text_to_search_for" /path/where/to/search

list file names and part of text
```
grep -ro --include "filename" -e "pattern" .
```
(-rho to suppress the file name)

find file based on its name (case insensitive)
```
find / -iname "file_name"
```
list files with a certain extension
```
find /path/where/to/search *.c
```

bash cheat sheet

Table of contents

Debian specific

Mac specific

Linux and Mac