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columns, less basher specific
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@bahamas10
bahamas10 committed Jan 23, 2017
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Expand Up @@ -7,8 +7,8 @@ on [this wiki](http://mywiki.wooledge.org), specifically this page:

http://mywiki.wooledge.org/BashGuide/Practices

If anything is not mentioned explicitly in this guide, it defaults to matching whatever
is outlined in the wiki.
If anything is not mentioned explicitly in this guide, it defaults to matching
whatever is outlined in the wiki.

Aesthetics
----------
Expand All @@ -17,9 +17,14 @@ Aesthetics

tabs.

### Columns

not to exceed 80.

### Semicolons

You don't use semicolons on the command line (I hope), don't use them in scripts.
You don't use semicolons on the command line (I hope), don't use them in
scripts.

``` bash
# wrong
Expand All @@ -33,8 +38,8 @@ echo "hello $name"

### Functions

Don't use the `function` keyword. All variables created in a function should be
made local.
Don't use the `function` keyword. All variables created in a function should
be made local.

``` bash
# wrong
Expand Down Expand Up @@ -73,12 +78,13 @@ fi

### Spacing

No more than 2 consecutive newline characters (ie. no more than 1 blank line in a row)
No more than 2 consecutive newline characters (ie. no more than 1 blank line in
a row)

### Comments

No explicit style guide for comments. Don't change someones comments for aesthetic reasons
unless you are rewriting or updating them.
No explicit style guide for comments. Don't change someones comments for
aesthetic reasons unless you are rewriting or updating them.

Bashisms
--------
Expand Down Expand Up @@ -163,7 +169,8 @@ Do **not** use the `let` command.

### Parameter Expansion

Always prefer [parameter expansion](http://mywiki.wooledge.org/BashGuide/Parameters#Parameter_Expansion)
Always prefer [parameter
expansion](http://mywiki.wooledge.org/BashGuide/Parameters#Parameter_Expansion)
over external commands like `echo`, `sed`, `awk`, etc.

``` bash
Expand Down Expand Up @@ -197,9 +204,8 @@ done

### Determining path of the executable (`__dirname`)

Simply stated, you can't know this for sure. If you are trying to find
out the full path of the executing program, you should rethink your software
design.
Simply stated, you can't know this for sure. If you are trying to find out the
full path of the executing program, you should rethink your software design.

See http://mywiki.wooledge.org/BashFAQ/028 for more information

Expand All @@ -209,8 +215,8 @@ http://daveeddy.com/2015/04/13/dirname-case-study-for-bash-and-node/

### Arrays and lists

Use bash arrays instead of a string separated by spaces (or newlines, tabs, etc.)
whenever possible
Use bash arrays instead of a string separated by spaces (or newlines, tabs,
etc.) whenever possible

``` bash
# wrong
Expand All @@ -226,16 +232,26 @@ for module in "${modules[@]}"; do
done
```

Of course, in this example it may be better expressed as:

``` bash
npm install -g "${modules[@]}"
```

... if the command supports multiple arguments, and you are not interested in
catching individual failures.

### read builtin

Use the bash `read` builtin whenever possible to avoid forking external commands
Use the bash `read` builtin whenever possible to avoid forking external
commands

Example

``` bash
fqdn='computer1.daveeddy.com'

IFS=. read hostname domain tld <<< "$fqdn"
IFS=. read -r hostname domain tld <<< "$fqdn"
echo "$hostname is in $domain.$tld"
# => "computer1 is in daveeddy.com"
```
Expand All @@ -250,12 +266,12 @@ when forking external commands like `awk`, `sed`, `grep`, etc. to be as
portable as possible.

When writing bash and using all the powerful tools and builtins bash gives you,
you'll find it very rare that you need to fork external commands.
you'll find it rare that you need to fork external commands.

### [UUOC](http://www.smallo.ruhr.de/award.html)

Don't use `cat(1)` when you don't need it. If programs support reading from stdin,
pass the data in using bash redirection.
Don't use `cat(1)` when you don't need it. If programs support reading from
stdin, pass the data in using bash redirection.

``` bash
# wrong
Expand All @@ -270,7 +286,7 @@ grep foo file

Prefer using a command line tools builtin method of reading a file instead of
passing in stdin. This is where we make the inference that, if a program says
it can read a file passed by name, it's probably more performant to do so.
it can read a file passed by name, it's probably more performant to do that.

Style
-----
Expand All @@ -292,21 +308,24 @@ foo="hello world"
bar='You are $USER'
```

All variables that will undergo word-splitting *must* be quoted (1). If no splitting
will happen, the variable may remain unquoted.
All variables that will undergo word-splitting *must* be quoted (1). If no
splitting will happen, the variable may remain unquoted.

``` bash
foo='hello world'

if [[ -n $foo ]]; then # no quotes needed - [[ ... ]] won't word-split variable expansions
if [[ -n $foo ]]; then # no quotes needed:
# [[ ... ]] won't word-split variable expansions

echo "$foo" # quotes needed
fi

bar=$foo # no quotes needed - variable assignment doesn't word-split
```

1. The only exception to this rule is if the code or bash controls the variable for the
duration of its lifetime. For instance, [basher](https://github.com/bahamas10/basher) has code like:
1. The only exception to this rule is if the code or bash controls the variable
for the duration of its lifetime. For instance,
[basher](https://github.com/bahamas10/basher) has code like:

``` bash
printf_date_supported=false
Expand All @@ -326,7 +345,8 @@ variable are controlled explicitly and not taken from a user or command.
Also, variables like `$$`, `$?`, `$#`, etc. don't required quotes because they
will never contain spaces, tabs, or newlines.

When in doubt however, [quote all expansions](http://mywiki.wooledge.org/Quotes).
When in doubt however, [quote all
expansions](http://mywiki.wooledge.org/Quotes).

### Variable Declaration

Expand All @@ -350,16 +370,18 @@ foobar=baz

### shebang

Bash is not always located at `/bin/bash`, so always use this line:
Bash is not always located at `/bin/bash`, so use this line:

``` bash
#!/usr/bin/env bash
```

Unless you have a reason to use something else.

### Error Checking

`cd`, for example, doesn't always work. Make sure to check for any possible errors
for `cd` (or commands like it) and exit or break if they are present.
`cd`, for example, doesn't always work. Make sure to check for any possible
errors for `cd` (or commands like it) and exit or break if they are present.

``` bash
# wrong
Expand All @@ -383,13 +405,10 @@ http://mywiki.wooledge.org/BashFAQ/105

Never.

---

None of the things listed in the link below will be accepted in this code base.

http://mywiki.wooledge.org/BashPitfalls
Extra
-----

This reference also has examples on how to fix these issues.
- http://mywiki.wooledge.org/BashPitfalls

License
-------
Expand Down

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