I Failed the Turing Test

All posts tagged linux

Redirect Console Output: stdout and stderr

Redirect Console Output: stdout and stderr

Posted on Author VintaPosted in DevOps

File descriptors:

  • 0: stdin
  • 1: stdout
  • 2: stderr
# redirect stdout to a file `test.log`
$ strace uptime > test.log
$ strace uptime 1> test.log

# redirect stderr to a file `test.log`
$ strace uptime 2> test.log

# redirect stderr to stdout
# &1 references the value of the file descriptor 1 (stdout)
$ sh /home/vinta/do_shit.sh > /tmp/do_shit.log 2>&1

# `2> 1` actually means that you redirect stderr to a file named `1`
$ sh /home/vinta/do_shit.sh > /tmp/do_shit.log 2> 1
$ cat 1

# redirect both stderr and stdout to file `test.log`
$ strace uptime &> test.log

# run a command in backgroud
$ long-running-command &

ref:
http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html
https://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/
https://www.brianstorti.com/understanding-shell-script-idiom-redirect/

tmux: The terminal multiplexer

tmux: The terminal multiplexer

Posted on Author VintaPosted in DevOps

tmux is a command-line tool that can create multiple virtual terminals in one terminal.

ref:
https://tmux.github.io/

Install

# on Ubuntu
$ sudo apt-get install tmux

 # on macOS
$ brew install tmux

$ tmux -V
tmux 2.6

Configurations

in ~/.tmux.conf

# prefix: Control + a
set -g prefix C-a

# kill-session: Control + a >> X
bind X confirm-before "kill-session -t ''"

# select-pane: Option + arrow key
bind -n M-Left select-pane -L
bind -n M-Right select-pane -R
bind -n M-Up select-pane -U
bind -n M-Down select-pane -D

# start numbering at 1
set -g base-index 1
set-window-option -g pane-base-index 1

# allow for faster key repetition
set -s escape-time 0

# rather than constraining window size to the maximum size of any client
# connected to the *session*, constrain window size to the maximum size of any
# client connected to *that window*. Much more reasonable.
# CAUTION: not compatible with iTerm2
setw -g aggressive-resize off

set -g status-left-length 40

set -g mouse on

# list of plugins
set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-sensible'

# initialize TMUX plugin manager (keep this line at the very bottom of tmux.conf)
run '~/.tmux/plugins/tpm/tpm'

After adding new plugins, you need to press Control + A >> I to fetch and install them.

ref:
https://github.com/tony/tmux-config/blob/master/.tmux.conf

Usage

$ tmux

$ tmux new -s your_project

$ tmux ls

$ tmux attach

$ tmux attach -t your_project

# list all windows with their layouts
$ tmux list-windows

$ tmux kill-session -t your_project

# kill all sessions
$ tmux kill-server

# reload settings
$ tmux source ~/.tmux.conf

Shortcut Keys

Control + a >> Shift + ?
list all shortcut keys

Control + a >> Shift + ""
split window horizontally

Control + a >> Shift + %
split window vertically

Control + a >> Arrow keys
Command + Option + Arrow keys
move the cursor between panels

Control + a >> d
dettach

Control + a >> c
create a new window

Control + a >> p
switch to the previous window

Control + a >> n
switch to the next window

Control + a >> w
Control + a >> 0-9
switch to window 0-9

Control + a >> [
enable copy mode, you can use Option + Up or Option + Down to scroll

Control + a >> Shift + &
kill the current window

Control + a >> X
kill the current session

ref:
http://manpages.ubuntu.com/manpages/zesty/en/man1/tmux.1.html

Tools

tmuxp

$ pip install tmuxp

An sample config:

in ~/.tmuxp/your_project.yaml

session_name: swag
windows:
- window_name: swag
  layout: main-horizontal
  focus: 'true'
  options:
    automatic-rename: 'off'
    main-pane-height: 35
  start_directory: ~/Projects/swag-server
  shell_command_before:
    - clear
  panes:
  - shell_command:
    - make up
  - shell_command:
    focus: 'true'
  - shell_command:
    - cd ../swag-bot
    - clear
$ tmuxp load swag

Layouts
https://tmuxp.git-pull.com/en/latest/examples.html

ref:
https://github.com/tony/tmuxp
https://github.com/tony/tmuxp-config

tmux-resurrect

Control + a >> Control + s
save tmux env

Control + a >> Control + r
restore tmux env

ref:
https://github.com/tmux-plugins/tmux-resurrect

Integration with iTerm2

You must create tmux session with -CC argument to integrate with iTerm2.

$ tmux ls && read session && tmux -CC attach -t ${session:-default} || tmux -CC new -s ${session:-default}

ref:
https://gitlab.com/gnachman/iterm2/wikis/TmuxIntegration