My collection of useful bash functions

Published: 2019-05-30 | Lastmod: 2019-09-12
Tags: command-line

Update: this article is no longer maintained. My dotfiles now live in git. Please see https://github.com/zwbetz-gh/dotfiles

---

This is a living document. If relevant, I include an example usage after the function definition. Functions are geared towards Mac, but can be easily adapted to Linux.

For easy copy-pasting, here they are in plain text.

bash_profile_open #

Open .bash_profile with vscode:

bash_profile_open() {
  code ~/.bash_profile
}

bash_profile_source #

Source .bash_profile changes:

bash_profile_source() {
  source ~/.bash_profile
}

pretty_print_path #

Pretty print PATH:

pretty_print_path() {
  echo $PATH | tr ':' '\n'
}

$ pretty_print_path
/home/zwbetz/bin
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin

log #

Log something and timestamp it:

log() {
  echo -e "[$(date +'%a %F %T %z')] ${@}"
}

$ log Some text here
[Thu 2019-05-30 21:58:08 -0500] Some text here

to_lowercase #

Convert string to lowercase:

to_lowercase() {
  local input="$([[ -p /dev/stdin ]] && cat - || echo "$@")"
  [[ -z "$input" ]] && return 1 
  echo "$input" | tr '[:upper:]' '[:lower:]' 
}

$ to_lowercase SOME TEXT
some text

$ echo SOME TEXT | to_lowercase 
some text

to_uppercase #

Convert string to uppercase:

to_uppercase() {
  local input="$([[ -p /dev/stdin ]] && cat - || echo "$@")"
  [[ -z "$input" ]] && return 1 
  echo "$input" | tr '[:lower:]' '[:upper:]' 
}

$ to_uppercase some text
SOME TEXT

$ echo some text | to_uppercase 
SOME TEXT

length #

Get string length:

length() {
  local input="$([[ -p /dev/stdin ]] && cat - || echo "$@")"
  [[ -z "$input" ]] && return 1 
  echo "${#input}"
}

$ length gohugo
6

$ echo gohugo | length 
6

iso_8601_date #

Get the current date in ISO 8601 format, as UTC.

iso_8601_date() {
  date -u +'%Y-%m-%dT%H:%M:%SZ'
}

$ iso_8601_date
2019-06-12T00:34:41Z

timestamp #

Generate a file-friendly timestamp.

timestamp() {
  date +'%Y-%m-%d_%H-%M-%S'
}

$ timestamp
2019-06-11_19-34-58

$ touch foo_$(timestamp).txt
$ ls
foo_2019-06-11_19-34-58.txt

count_bytes #

count_bytes() {
  wc -c < "$1" | tr -d ' '
}

$ printf "My life has been the poem I would have writ\nBut I could not both live and utter it.\n" > foo.txt
$ count_bytes foo.txt
84

count_chars #

count_chars() {
  wc -m < "$1" | tr -d ' '
}

$ printf "My life has been the poem I would have writ\nBut I could not both live and utter it.\n" > foo.txt
$ count_chars foo.txt
84

count_words #

count_words() {
  wc -w < "$1" | tr -d ' '
}

$ printf "My life has been the poem I would have writ\nBut I could not both live and utter it.\n" > foo.txt
$ count_words foo.txt
19

count_lines #

count_lines() {
  wc -l < "$1" | tr -d ' '
}

$ printf "My life has been the poem I would have writ\nBut I could not both live and utter it.\n" > foo.txt
$ count_lines foo.txt
2

http_status_code #

http_status_code() {
  local input="$([[ -p /dev/stdin ]] && cat - || echo "$@")"
  [[ -z "$input" ]] && return 1
  curl -I -s -o /dev/null -w "%{http_code}\n" "$input"
}

$ http_status_code https://gohugo.io/
200

$ echo https://gohugo.io/ | http_status_code
200

merge_hugo_themes #

merge_hugo_themes() {
  git submodule update --remote --merge
  git add . 
  git commit -m "Theme changes" 
  git push 
}