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added more examples

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Dylan Araps 2018-06-15 09:37:35 +10:00
parent 9f43812680
commit 7ab77b6024
1 changed files with 125 additions and 101 deletions
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@ -522,6 +522,8 @@ Alternative to the `head` command.
**NOTE:** Requires `bash` 4+
**Example Function:**
```sh
head() {
# Usage: head "n" "file"
@ -530,12 +532,25 @@ head() {
}
```
**Example Usage:**
```shell
$ head 2 ~/.bashrc
# Prompt
PS1='➜ '
$ head 1 ~/.bashrc
# Prompt
```
### Get the last N lines of a file.
Alternative to the `tail` command.
**NOTE:** Requires `bash` 4+
**Example Function:**
```sh
tail() {
# Usage: tail "n" "file"
@ -550,6 +565,8 @@ Alternative to `wc -l`.
**NOTE:** Requires `bash` 4+
**Example Function:**
```sh
lines() {
# Usage lines "file"
@ -593,6 +610,8 @@ _() {
This works by passing the output of the glob as function arguments. We
then count the arguments and print the number.
**Example Function:**
```sh
count() {
# Usage: count /path/to/dir/*
@ -622,6 +641,8 @@ _() {
Alternative to the `dirname` command.
**Example Function:**
```sh
dirname() {
# Usage: dirname "path"
@ -633,6 +654,8 @@ dirname() {
Alternative to the `basename` command.
**Example Function:**
```sh
basename() {
# Usage: basename "path"
@ -678,6 +701,8 @@ _() {
### Convert a hex color to RGB.
**Example Function:**
```sh
hex_to_rgb() {
# Usage: hex_to_rgb "#FFFFFF"
@ -691,6 +716,8 @@ hex_to_rgb() {
### Convert an RGB color to hex.
**Example Function:**
```sh
rgb_to_hex() {
# Usage: rgb_to_hex "r" "g" "b"
@ -705,6 +732,8 @@ rgb_to_hex() {
This is handy when writing scripts in pure bash and `stty`/`tput` can’t be
called.
**Example Function:**
```sh
get_term_size() {
# Usage: get_term_size
@ -720,6 +749,8 @@ get_term_size() {
**NOTE**: This does not work in some terminal emulators.
**Example Function:**
```sh
get_window_size() {
# Usage: get_window_size
@ -733,6 +764,8 @@ get_window_size() {
This is useful when creating a TUI in pure bash.
**Example Function:**
```sh
get_cursor_pos() {
# Usage: get_cursor_pos
@ -745,76 +778,67 @@ get_cursor_pos() {
### Shorter `for` loop syntax.
```sh
_() {
# Tiny C Style.
for((;i++<10;)){ echo "$i";}
```shell
# Tiny C Style.
for((;i++<10;)){ echo "$i";}
# Undocumented method.
# Note: This is commented to make shellcheck play nice.
# for i in {1..10};{ echo "$i";}
# Undocumented method.
# Note: This is commented to make shellcheck play nice.
# for i in {1..10};{ echo "$i";}
# Expansion.
for i in {1..10}; do echo "$i"; done
# Expansion.
for i in {1..10}; do echo "$i"; done
# C Style.
for((i=0;i<=10;i++)); do echo "$i"; done
}
# C Style.
for((i=0;i<=10;i++)); do echo "$i"; done
```
### Shorter infinite loops.
```sh
_() {
# Normal method
while :; do echo hi; done
```shell
# Normal method
while :; do echo hi; done
# Shorter
for((;;)){ echo hi;}
}
# Shorter
for((;;)){ echo hi;}
```
### Shorter function declaration.
```sh
_() {
# Normal method
f(){ echo hi;}
```shell
# Normal method
f(){ echo hi;}
# Using a subshell
f()(echo hi)
# Using a subshell
f()(echo hi)
# Using arithmetic
# You can use this to assign integer values.
# Example: f a=1
# f a++
f()(($1))
# Using arithmetic
# You can use this to assign integer values.
# Example: f a=1
# f a++
f()(($1))
# Using tests, loops etc.
# NOTE: You can also use ‘while’, ‘until’, ‘case’, ‘(())’, ‘[[]]’.
# NOTE: These are commented to make shellcheck play nice.
# f()if true; then echo "$1"; fi
# f()for i in "$@"; do echo "$i"; done
}
# Using tests, loops etc.
# NOTE: You can also use ‘while’, ‘until’, ‘case’, ‘(())’, ‘[[]]’.
f()if true; then echo "$1"; fi
f()for i in "$@"; do echo "$i"; done
```
### Shorter `if` syntax.
```sh
_() {
# One line
[[ "$var" == hello ]] && echo hi || echo bye
[[ "$var" == hello ]] && { echo hi; echo there; } || echo bye
```shell
# One line
[[ "$var" == hello ]] && echo hi || echo bye
[[ "$var" == hello ]] && { echo hi; echo there; } || echo bye
# Multi line (no else, single statement)
[[ "$var" == hello ]] && \
echo hi
# Multi line (no else, single statement)
[[ "$var" == hello ]] && \
echo hi
# Multi line (no else)
[[ "$var" == hello ]] && {
echo hi
# ...
}
# Multi line (no else)
[[ "$var" == hello ]] && {
echo hi
# ...
}
```
@ -825,31 +849,29 @@ statement. The `$_` variable stores the last argument of the last
successful command. `:` always succeeds so we can abuse it to store the
variable value.
```sh
_() {
# Example snippet from Neofetch.
case "$(uname)" in
"Linux" | "GNU"*)
: "Linux"
;;
```shell
# Example snippet from Neofetch.
case "$(uname)" in
"Linux" | "GNU"*)
: "Linux"
;;
*"BSD" | "DragonFly" | "Bitrig")
: "BSD"
;;
*"BSD" | "DragonFly" | "Bitrig")
: "BSD"
;;
"CYGWIN"* | "MSYS"* | "MINGW"*)
: "Windows"
;;
"CYGWIN"* | "MSYS"* | "MINGW"*)
: "Windows"
;;
*)
printf '%s\n' "Unknown OS detected, aborting..." >&2
exit 1
;;
esac
*)
printf '%s\n' "Unknown OS detected, aborting..." >&2
exit 1
;;
esac
# Finally, set the variable.
os="$_"
}
# Finally, set the variable.
os="$_"
```
## Internal Variables
@ -862,60 +884,60 @@ http://tldp.org/LDP/abs/html/internalvariables.html
### Get the location to the `bash` binary.
```sh
: "$BASH"
```shell
"$BASH"
```
### Get the version of the current running `bash` process.
```sh
```shell
# As a string.
: "$BASH_VERSION"
"$BASH_VERSION"
# As an array.
: "${BASH_VERSINFO[@]}"
"${BASH_VERSINFO[@]}"
```
### Open the user's preferred text editor.
```sh
: "$EDITOR" "$file"
```shell
"$EDITOR" "$file"
# NOTE: This variable may be empty, set a fallback value.
: "${EDITOR:-vi}" "$file"
"${EDITOR:-vi}" "$file"
```
### Get the name of the current function.
```sh
```shell
# Current function.
: "${FUNCNAME[0]}"
"${FUNCNAME[0]}"
# Parent function.
: "${FUNCNAME[1]}"
"${FUNCNAME[1]}"
# So on and so forth.
: "${FUNCNAME[2]}"
: "${FUNCNAME[3]}"
"${FUNCNAME[2]}"
"${FUNCNAME[3]}"
# All functions including parents.
: "${FUNCNAME[@]}"
"${FUNCNAME[@]}"
```
### Get the host-name of the system.
```sh
: "$HOSTNAME"
```shell
"$HOSTNAME"
# NOTE: This variable may be empty.
# Optionally set a fallback to the hostname command.
: "${HOSTNAME:-$(hostname)}"
"${HOSTNAME:-$(hostname)}"
```
### Get the architecture of the Operating System.
```sh
: "$HOSTTYPE"
```shell
"$HOSTTYPE"
```
### Get the name of the Operating System / Kernel.
@ -923,22 +945,22 @@ http://tldp.org/LDP/abs/html/internalvariables.html
This can be used to add conditional support for different Operating
Systems without needing to call `uname`.
```sh
: "$OSTYPE"
```shell
"$OSTYPE"
```
### Get the current working directory.
This is an alternative to the `pwd` built-in.
```sh
: "$PWD"
```shell
"$PWD"
```
### Get the number of seconds the script has been running.
```sh
: "$SECONDS"
```shell
"$SECONDS"
```
## Other
@ -950,6 +972,8 @@ in place of the `date` command in a lot of cases.
**NOTE:** Requires `bash` 4+
**Example Function:**
```sh
date() {
# Usage: date "format"
@ -971,22 +995,22 @@ date() {
### Bypass shell aliases.
```sh
```shell
# alias
: ls
ls
# command
# shellcheck disable=SC1001
: \ls
\ls
```
### Bypass shell functions.
```sh
```shell
# function
: ls
ls
# command
: command ls
command ls
```