Concatenation of strings within functions

Question

I am having a weird problem with bash scripts.

I have two scripts: vlan_menu and the other network_menu. network_menu sources vlan_menu and calls configure_v().

Inside vlan_menu, I do this:

function configure_v() {
    TAG_V=66
    str="team0."
    newtag="$(echo ${str}${TAG_V})"
    ${SCRIPTS}/system_config -e ${newtag} ...
    echo ${newtag} >&2
}

when I run vlan_menu and print the value of ${newtag}, Isee: "team0.66" which is what I want to see.

network_menu:

source vlan_menu
configure_v;

When I run network_menu, the output of the echo is: "team0. 66"

Why does this happen? Please help.

Your error is not apparent from the snippet you have posted. If there is intervening code between source vlan_menu and configure_v, then it should be posted as well. (see the answer why using command-substitution with echo to assign a concatenated string is wrong -- well, at least, totally unnecessary) — David C. Rankin
– David C. Rankin, Commented May 4, 2016 at 6:06

heemayl · Accepted Answer · 2016-05-04 03:15:43Z

2

You should use the simpler expression:

newtag="${str}${TAG_V}"

edited May 4, 2016 at 3:15

heemayl

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answered May 4, 2016 at 1:34

John Zwinck

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2 Comments

John Kugelman Over a year ago

The quotes and braces are both optional as well. newtag=$str$TAG_V is equivalent.

Michael Vehrs Over a year ago

True, but I don't see how that causes the OP's problem.

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