Silas Sewell

A simple function to slice strings in Bash similar to Python's string slicing functionality.

Examples

[silas@pluto ~]$ string_slice "12345" 0 1
1
[silas@pluto ~]$ string_slice "12345" 0 3
123
[silas@pluto ~]$ string_slice "12345" 2 3
3
[silas@pluto ~]$ string_slice "12345" 2 -2
3
[silas@pluto ~]$ string_slice "12345" -3
345

Implementation

function string_slice {
    STRING="$1"
    declare -i LENGTH="${#STRING}"
    declare -i START="$2"
    declare -i END="$3"
    if [ $START -lt 0 ]; then
        START=$[ $LENGTH + $START ]
    fi
    if [ $END -le 0 ]; then
        END=$[ $LENGTH + $END ]
    fi
    START=$[ $START + 1 ]
    (echo "$STRING" | cut -c $START-$END) 2> /dev/null
}

The following describes a simple way to manage you profile configuration files using GitHub.

Features

• Centralized configuration management
• Files live in their native locations (no symbolic linking)
• Home directory is not a Git repository
• All the power of git with a simple alias

Setup Repository

• Log into GitHub and create a repository named config
• Add your public keys to GitHub (if you haven't done so already)

• Open a terminal and switch to your home directory

  cd ~
  

• Create a configuration directory

  mkdir .config.git
  

• Add the following alias to your current session and your .bash_profile

  alias config='git --git-dir=$HOME/.config.git/ --work-tree=$HOME'
  echo "alias config='git --git-dir=$HOME/.config.git/ --work-tree=$HOME'" >> .bash_profile
  

• Add your .bash_profile to the configuration repository

  config add .bash_profile
  

• Commit the changes

  config commit -m 'Initial commit'
  

• Change the origin to GitHub

  config remote add origin git@github.com:GITHUB_USERNAME/config.git
  

• Push the changes

  config push origin master
  

If you get an error when running config pull to the effect of You asked me to pull without... run the follow:

    echo -e '[branch "master"]\n  remote = origin\n  merge = refs/heads/master' >> ~/.config.git/config

Setup Configuration Management on a Different System

1. Add your public keys to GitHub (if you haven't done so already)

2. Switch to your home directory

   cd ~
   

3. Backup your local configuration files, example:

   mv .bash_profile .bash_profile.bk
   

4. Clone your configuration repository

   git clone git@github.com:GITHUB_USERNAME/config.git config.git
   

5. Move the git metadata to ~/.config.git

   mv config.git/.git .config.git
   

6. Enable dotglob

   shopt -s dotglob
   

7. Move your configuration files to your home directory

   mv -i config.git/* .
   

8. Delete the config.git directory

   rmdir config.git
   

9. Logout and log back in

Basic Usage

• config pull - get latest configuration changes
• config add FILENAME - add a configuration file
• config commit -a - save all configuration changes
• config push - push configuration changes to GitHub
• and any other config GIT_OPTION

You can see my configuration repository at http://github.com/silas/config.

Source: Manage your $HOME with git by Robert Escriva

The following is a simple Bash function you can paste into your bashrc file to start Python/IPython depending on the context.

~/.bashrc

function python {
    IPYTHON="/usr/bin/ipython"
    PYTHON="/usr/bin/python"

    if [[ -n $1 ]]; then
        $PYTHON $@
    elif [[ -e $IPYTHON ]]; then
        $IPYTHON
    else
        $PYTHON
    fi
}

Manage SSH Tunnel is a simple shell script to start and stop ssh tunnels from the terminal.

Setup

Note: the setup assumes bash as the default shell

1. Download tunnel.sh and save it to ~/bin/

2. Add to ~/.bash_profile or ~/.bashrc

   alias tunnel_home='/bin/sh ~/bin/tunnel.sh example.net sam 22 8888'
   

3. Replace example.net with the hostname of the server, sam with the username on the server, and 8888 with the local tunnel port

4. Type source ~/.bash_profile or source ~/.bashrc

Usage

1. To open the tunnel

   tunnel_home start
   

2. To close the tunnel

   tunnel_home close