Linux: set command for local variables

Question

I am trying to understand local/environment variables and export/set commands.

$ set FILEM="razrax"
$ echo $FILEM

$ FILEN="test"
$ echo $FILEN
test

Please explain why echo $FILEM returns empty string

Answer 1

You're confusing bash with csh.

In bash like in any Bourne-like shell, set is the command to set options (shell configuration settings like -f, -C, -o noclobber...) and positional parameters ($1, $2...).

set FILEM="razrax"

Sets $1 to FILEM=razrax.

$ set FILEM="razrax"
$ echo "$1"
FILEM=razrax

The syntax for variable assignment in Bourne-like shells is:

VAR=value

(no space allowed on either side of =).

ksh and some other Bourne-like shells (mksh, pdksh, zsh) can also assign array variables with set though:

set -A array value1 value2

zsh, bash, yash and newer versions of ksh use this syntax instead:

array=(value1 value2)

In contrast, in csh or tcsh, the syntax is:

set VAR = value
set array = (value1 value2)

(spaces around = optional).

In rc/es shells:

VAR = value
array = (value1 value2)

(spaces around = optional).