Shell Functions

There are plenty of shell functions it would convenient to retain.

Predicates

Bash offers a number of predicates which we can re-imagine and maybe (maybe not!) avoid some legacy. In particular, Bash uses upper-case -S to test if a file is a socket whereas all the other file predicates are in lower-case. In addition, rather than -h or -L for testing for a symbolic link we can use l?.

We can now use upper-case predicates for other objects, notably, file descriptors, eg. T? for terminals.

function b? pathname

Is pathname a block special device?

Param pathname:

pathname to test

Type pathname:

string

function c? pathname

Is pathname a character special device?

Param pathname:

pathname to test

Type pathname:

string

function d? pathname

Is pathname a directory?

Param pathname:

pathname to test

Type pathname:

string

function e? pathname

Does pathname exist?

Param pathname:

pathname to test

Type pathname:

string

function f? pathname

Is pathname a regular file?

Param pathname:

pathname to test

Type pathname:

string

function l? pathname

Is pathname a symlink?

Param pathname:

pathname to test

Type pathname:

string

function p? pathname

Is pathname a FIFO?

Param pathname:

pathname to test

Type pathname:

string

function r? pathname

Does pathname satisfy libc/access pathname libc/R_OK?

Param pathname:

pathname to test

Type pathname:

string

function s? pathname

Is pathname a socket?

Param pathname:

pathname to test

Type pathname:

string

function T? fd

Is fd a terminal?

Param fd:

file descriptor to test

Type fd:

C/int

function w? pathname

Does pathname satisfy libc/access pathname libc/W_OK?

Param pathname:

pathname to test

Type pathname:

string

function x? pathname

Does pathname satisfy libc/access pathname libc/X_OK?

Param pathname:

pathname to test

Type pathname:

string

Last built at 2025-10-28T07:10:59Z+0000 from 463152b (dev)