Linux, bash and cygwin tips and tricks

LINUX , UNIX , BASH AND CYGWIN TIPS AND TRICKS

This document contains linux unix bash cygwin related code snippets

1. FILE AND DIRS MANAGEMENT

This section contains tips and tricks on files and dirs management.

1.1. how-to create a symlink

how-to create a symlink

# START === create symlink
export link_path=/vagrant
export target_path=/mnt/hgfs/vagrant
mkdir -p `dirname $link_path`
unlink $link_path
ln -s "$target_path" "$link_path"
ls -la $link_path;
# STOP === create symlink

1.2. how-to search and replace line feeds in a selection in excel

1. Select the cells.
2. Ctrl + H to present the find and replace dialog
3. For search: press the Alt num and from the Num keyboard type : 013 or 011
4. For replace: type the char to replace with
5. Replace all the occurrencies by : Alt + A

1.3. how-to search and replace strings in file contents recursively

In order to search and replace strings in the file and dir contents perform the copy paste the following code in your bash shell terminal.

# START -- how-to search and replace recursively 
export dir=/var/aktia/3rdparty/docs/docx; 
export to_search="emric"
export to_replace="t24"

#-- search and replace in file contents
find "$dir/" -type f -exec perl -pi -e "s#$to_search#$to_replace#g" {} \;
find "$dir/" -type f -name '*.bak' | xargs rm -f
# STOP  -- how-to rename files recursively

1.4. how-to search and replace strings in file and dirnames recursively

In order to search and replace strings in the file and dir paths perform the copy paste the following code in your bash shell terminal.

# START -- how-to search and replace recursively 
export dir=/var/aktia/3rdparty/docs/docx; 
export to_search="emric"
export to_replace="t24"
#-- search and replace in file names
find "$dir/" -type d |\
perl -nle '$o=$_;s#'"$to_search"'#'"$to_replace"'#g;$n=$_;`mkdir -p $n` ;'
find "$dir/" -type f |\
perl -nle '$o=$_;s#'"$to_search"'#'"$to_replace"'#g;$n=$_;rename($o,$n) unless -e $n ;'

2. PACKING AND UNPACKING

Bunch of commands for packing and unpacking on Linux

2.1. how-to unpack a *.tar.gz package

Run the followint commands in the bash shell:

export dir=<>
cd $dir
# upack !!!
gzip -dc *.tar.gz | tar xvf -

2.2. how-to unpack a tar package

how-to unpack a tar package

#how-to unpack tar file
tar xvf $file

2.3. how-to check which ports are listening

how-to check which ports are listening + others netstta

# which processes are listening on my system
netstat --tcp --listening --programs
netstat --tcp
netstat --route

2.4. how-to implement public private key authentication

Start on the client , check the comments when to move on the server.

# START === how-to implement public private key ( pkk ) authentication 
# create pub priv keys on server
# START copy 
ssh-keygen -t rsa
# copy the rsa pub key to the ssh server
scp ~/.ssh/id_rsa.pub $ssh_user@$ssh_server:/home/$ssh_user/


# STOP copy  
# Hit enter twice 
# START copy 
cat id_rsa.pub >> ~/.ssh/authorized_keys
cat ~/.ssh/authorized_keys
chmod -v 0700 ~/.ssh
chmod -v 0600 ~/.ssh/authorized_keys
chmod -v 0600 ~/.ssh/id_rsa
chmod -v 0644 ~/.ssh/id_rsa.pub
find ~/.ssh -exec stat -c "%U:%G %a %n" {} \;
rm -fv ~/id_rsa.pub
# STOP COPY

# START copy 
ssh-keygen -t dsa
# STOP copy  
# Hit enter twice 
# START copy 
cat id_dsa.pub >> ~/.ssh/authorized_keys
cat ~/.ssh/authorized_keys
chmod -v 0700 ~/.ssh
chmod -v 0600 ~/.ssh/authorized_keys
chmod -v 0600 ~/.ssh/id_dsa
chmod -v 0644 ~/.ssh/id_dsa.pub
find ~/.ssh -exec stat -c "%U:%G %a %n" {} \;
rm -fv ~/id_dsa.pub
# STOP COPY
# STOP === how-to implement public private key authentication