Oils Reference — Chapter Special Variables

This chapter describes special variables for OSH and YSH.

(in progress)

In This Chapter

YSH Vars

ARGV

Replacement for "$@"

ENV

TODO

_this_dir

The directory the current script resides in. This knows about 3 situations:

It's useful for "relative imports".

YSH Status

_status

DEPRECATED: Use _error.code instead.

_error

A Dict that's set by the try builtin.

The integer _error.code is always present:

try {
  ls /tmp
}
echo "status is $[_error.code]"

Some errors also have a message field, like JSON/J8 encoding/decoding errors, and user errors from the error builtin.

try {
  echo $[toJson( /d+/ )]  # invalid Eggex type
}
echo "failed: $[_error.message]"  # => failed: Can't serialize ...

_pipeline_status

After a pipeline of processes is executed, this array contains the exit code of each process.

Each exit code is an Int. Compare with PIPESTATUS.

_process_sub_status

The exit status of all the process subs in the last command.

YSH Tracing

SHX_indent

SHX_punct

SHX_pid_str

YSH Read

_reply

YSH read sets this variable:

read --all < myfile
echo $_reply

Oils VM

OILS_VERSION

The version of Oils that's being run, e.g. 0.23.0.

LIB_OSH

The string ///osh, which you can use with the source builtin.

source $LIB_OSH/two.sh    

LIB_YSH

The string ///ysh, which you can use with the source builtin.

source $LIB_YSH/yblocks.ysh

OILS_GC_THRESHOLD

At a GC point, if there are more than this number of live objects, collect garbage.

OILS_GC_ON_EXIT

Set OILS_GC_ON_EXIT=1 to explicitly collect and free() before the process exits. By default, we let the OS clean up.

Useful for ASAN testing.

OILS_GC_STATS

When the shell process exists, print GC stats to stderr.

OILS_GC_STATS_FD

When the shell process exists, print GC stats to this file descriptor.

Float

NAN

The float value for "not a number".

(The name is consistent with the C language.)

INFINITY

The float value for "infinity". You can negate it to get "negative infinity".

(The name is consistent with the C language.)

Shell Vars

IFS

Used for word splitting. And the builtin shSplit() function.

LANG

TODO: bash compat

GLOBIGNORE

TODO: bash compat

Shell Options

SHELLOPTS

bash compat: serialized options for the set builtin.

BASHOPTS

bash compat: serialized options for the shopt builtin.

Other Env

HOME

$HOME is used for:

  1. ~ expansion
  2. ~ abbreviation in the UI (the dirs builtin, \W in $PS1).

Note: The shell doesn't set $HOME. According to POSIX, the program that invokes the login shell sets it based on /etc/passwd.

PATH

A colon-separated string that's used to find executables to run.

POSIX Special

Other Special

BASH_REMATCH

Result of regex evaluation [[ $x =~ $pat ]].

PIPESTATUS

After a pipeline of processes is executed, this array contains the exit code of each process.

Each exit code is a Str. Compare with _pipeline_status.

Platform

HOSTNAME

The name of the "host" or machine that Oils is running on, determined by gethostname().

OSTYPE

The operating system that Oils is running on, determined by uname().

Examples: linux darwin ...

Call Stack

BASH_SOURCE

FUNCNAME

BASH_LINENO

Tracing

LINENO

Process State

BASHPID

TODO

PPID

TODO

UID

EUID

Process Stack

Shell State

Completion

COMP_WORDS

An array of words, split by : and = for compatibility with bash. New completion scripts should use COMP_ARGV instead.

COMP_CWORD

Discouraged; for compatibility with bash.

COMP_LINE

Discouraged; for compatibility with bash.

COMP_POINT

Discouraged; for compatibility with bash.

COMP_WORDBREAKS

Discouraged; for compatibility with bash.

COMPREPLY

User-defined completion functions should Fill this array with candidates. It is cleared on every completion request.

COMP_ARGV

An array of partial command arguments to complete. Preferred over COMP_WORDS. The compadjust builtin uses this variable.

(An OSH extension to bash.)

History

HISTFILE

Override the default OSH history location.

YSH_HISTFILE

Override the default YSH history location.

cd

PWD

OLDPWD

CDPATH

getopts

OPTIND

OPTARG

OPTERR

read

REPLY

OSH read sets this:

read < myfile

Functions

RANDOM

bash compat

SECONDS

bash compat

Generated on Sun, 28 Jul 2024 05:44:54 +0000