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Assignment operator without operand

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# 1  
Old 08-22-2014
Assignment operator without operand
Does anyone know how this line in bash works?

Code:
local gotbase= force= nicelevel corelimit
local pid base= user= nice= bg= pid_file=
local cgroup=

These lines are part of the daemon function inside the "functions" file at /etc/init.d in RH.
Last edited by Don Cragun; 08-22-2014 at 06:06 PM.. Reason: Change bold tags to CODE tags, add missing ICODE tags.
# 2  
Old 08-22-2014
All of the variables listed are tagged as "local"; gotbase, force, base, user, nice, pid_file, and cgroup are explicitly initialized to empty strings.
# 3  
Old 08-22-2014
Most tests check for unset or null values.

Code:
mute@thedoctor:~$ f() { local foo; [[ $foo ]] || echo empty; }; f
empty
mute@thedoctor:~$ f() { local foo=; [[ $foo ]] || echo empty; }; f
empty

But you'll see a difference with something like this:

Code:
mute@thedoctor:~$ f() { local foo=; : ${foo=unset}; declare -p foo; }; f
declare -- foo=""
mute@thedoctor:~$ f() { local foo; : ${foo=unset}; declare -p foo; }; f
declare -- foo="unset"

This User Gave Thanks to neutronscott For This Post:
Rameshck
# 4  
Old 08-22-2014
Quote:
Originally Posted by Don Cragun
All of the variables listed are tagged as "local"; gotbase, force, base, user, nice, pid_file, and cgroup are explicitly initialized to empty strings.
Thanks Don. SmilieSmilie

---------- Post updated at 03:27 PM ---------- Previous update was at 03:16 PM ----------

Quote:
Originally Posted by neutronscott
Most tests check for unset or null values.

Code:
mute@thedoctor:~$ f() { local foo; [[ $foo ]] || echo empty; }; f
empty
mute@thedoctor:~$ f() { local foo=; [[ $foo ]] || echo empty; }; f
empty

But you'll see a difference with something like this:

Code:
mute@thedoctor:~$ f() { local foo=; : ${foo=unset}; declare -p foo; }; f
declare -- foo=""
mute@thedoctor:~$ f() { local foo; : ${foo=unset}; declare -p foo; }; f
declare -- foo="unset"

Thanks neutronscott,
Looks like they had a reason for explicitly declaring them and setting them to empty strings.
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