Navigating Shell for Productivity and Profit

I hope you find inspirations from these pretty neat shell tricks and my shell setup.

Array Expansion

Use Array Expansion to quickly build arguments to a command. For example, to download several HTTP resources:

$ wget https://kubernetespodcast.com/episodes/KPfGep{001..062}.mp3

To rename files when you just want to change a substring.

$ mv /path/to/same-prefix-{old,new}.txt

Process Substitution and Anonymous Files

<() redirects the stdout of the command in the subshell to a file descriptor opened at /dev/fd. This is known as process substitution.

$ sh <(curl -sL https://istio.io/downloadIstioctl)

The above is equivalent to the following, where - means to use the stdin as a file.

$ curl -sL https://istio.io/downloadIstioctl | sh -

Note that process substitution is more powerful than pipes, since you can do things like

$ diff <(ssh somehost cat /etc/hosts) <(ssh some-other-host cat /etc/hosts)

Start new shell

Just updated your bashrc/zshrc file, but want to hold on to your environment variables, file descriptors, etc? Do this.

$ exec -l $SHELL

The password is sudo

Dealing with production outage and in dire need of mitigation?

$ sudo su

And then you are always the root master. “I don’t test in prod; I dev in prod.”

Alias for the Win

Type less. Move fast. Here are some I use everyday.

mcd() { mkdir -p "$1" && cd "$1" }
cdl() { cd "$1" &&  ls }

alias ls='ls -F -G'
alias ll='ls -lh'
alias o='open'
alias ping='ping -c 5'
alias gauth='gcloud auth login --update-adc'

(I consider it a work injury that I now quote everything in shell and has long stopped using white space in file names even for personal stuff. Maybe you are like me.)

Command Deletion

In-line file

cat << EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
EOF

Search Command History with Fuzzy Find

You probably know you could use ctrl+r to retrieve a previously executed command quickly, but it only gives you one suggestion. fzf solves it not only for commands but finds files as well.