pure-bash-bible/manuscript/chapter16.txt

# INTERNAL VARIABLES

## Get the location to the `bash` binary

```shell
"$BASH"
```

## Get the version of the current running `bash` process

```shell
# As a string.
"$BASH_VERSION"

# As an array.
"${BASH_VERSINFO[@]}"
```

## Open the user's preferred text editor

```shell
"$EDITOR" "$file"

# NOTE: This variable may be empty, set a fallback value.
"${EDITOR:-vi}" "$file"
```

## Get the name of the current function

```shell
# Current function.
"${FUNCNAME[0]}"

# Parent function.
"${FUNCNAME[1]}"

# So on and so forth.
"${FUNCNAME[2]}"
"${FUNCNAME[3]}"

# All functions including parents.
"${FUNCNAME[@]}"
```

## Get the host-name of the system

```shell
"$HOSTNAME"

# NOTE: This variable may be empty.
# Optionally set a fallback to the hostname command.
"${HOSTNAME:-$(hostname)}"
```

## Get the architecture of the Operating System

```shell
"$HOSTTYPE"
```

## Get the name of the Operating System / Kernel

This can be used to add conditional support for different Operating
Systems without needing to call `uname`.

```shell
"$OSTYPE"
```

## Get the current working directory

This is an alternative to the `pwd` built-in.

```shell
"$PWD"
```

## Get the number of seconds the script has been running

```shell
"$SECONDS"
```

## Get a pseudorandom integer

Each time `$RANDOM` is used, a different integer between `0` and `32767` is returned. This variable should not be used for anything related to security (*this includes encryption keys etc*).


```shell
"$RANDOM"
```

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