Tag Archives: Bash

TMUX Easy Hotkeys + Lean Command Prompt

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This is just a simple note of some TMUX and BASH profile configuration that I find helpful when developing.

Tmux lets you split screens arbitrarily.  So, you can divide one terminal up into, say, 1 half-screen, full width panel up top and 2, quarter-screen panels on the bottom.  Generally, you have to hop around by pushing ctrl + b and then a key (like % or “) to split a screen into multiple panels horizontally or vertically.  Equally, you do ctrl +b and an arrow key to move between panes.

Two problems with this are:

  • ctrl+b is an awful hot key, it’s hard to reach and you’ll use it constantly.
  • Once you end up in quarter-size screens, even on big monitors, your default terminal prompt (the thing that shows up before you type commands) becomes too large for comfortable use.

TMUX Config

Edit (or create) the file ~/.tmux.conf to customize tmux.  Then add these lines.  The first two switch the ctrl + b hotkey to ctrl + a (which is much more convenient for constant use).  The others are just nice fixes to have around for other reasons.

# remap prefix from 'C-b' to 'C-a'
unbind C-b
set-option -g prefix C-a

#Fix some annoying behavior that makes some keys not work.
bind-key C-a send-prefix

# Start window numbering at 1
set -g base-index 1

Bash Profile Prompt Config

Edit your ~/.bashrc file (your bash profile).  If a line for PS1= already exists, you’ll want to comment it out or modify it, otherwise just add this in:

PS1="\u:\W$ "

This changes your terminal prompt to only show .  So, for example, if my name is John and I’m working in a folder called /opt/code, it would just display john:code vs a full path name with additional info (which takes up way too much space on quarter-size panes).

I hope you find this useful, and thanks for reading!

 

Bash xargs – Use Anywhere in Your Command

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If you want to use the xargs command to build a new command and place the standard input from your stream wherever you like (or in multiple places), here is an example:

Let’s say we have a hosts file:

111.222.111.222 host1.mydomain.com
222.111.222.111 host2.mydomain.com

We can take out the first column with awk (the IP column), and we can pipe it to xargs and use -I. Then we can use the % sign to both ssh to the IP and to display a message with the IP written from the host.

This is obviously very flexible and useful for pretty much any command you’re building from earlier inputs :).

cat dynamic_hosts | awk '{print $1}' | xargs -I % ssh % "echo hi from %"

Use wget with self-signed certificate and output to stdout

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Not much of an article here… but if you want to use WGET to validate a spring boot app with a self-signed certificate, for example, and you don’t want to bother outputting the results to file, you can do this:

wget -q -O – https://172.20.234.165/actuator/health –no-check-certificate

The output would be right inline and would avoid the certificate validation:

# wget -q -O – https://172.20.234.165/actuator/health –no-check-certificate
{“status”:”UP”} #

You could achieve this with curl as well I’m sure – but it isn’t installed on alpine it seems and I didn’t want to install extra tools.

 

Bash – Grep (or Run Other Command) Only On Files Created This Week, Day.

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Use Case

I just ran into a simple problem where I had to grep files on a server, but the directory had TONS and TONS of files in it.  I just wanted to target files created within the last week or so.

Working Command

It turns out this find command is very handy for this occasion.  It was taken and lightly modified from this unix stack-exchange post after a fair bit of searching.

find . -mtime -7 -exec grep "my_search_string" {} \;

Basically, it finds everything in “.” (the current directory) that was created in the last 7 days (as in 24 hour days, not from-this-morning days), and it executes the grep expression on it.

You can modify the timing however you want with mtime as well as change the target directory or command to execute, and of course you can pipe the output to whatever you want :).