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asaba90

Member

Registered: 2015-03-06

Posts: 7

How to put apostrophe in variable

I am writing a simple script which uses rsync. Sometimes i want to provide a different port for ssh like this:
rsync -e 'ssh -p 1234' ....
I have a variable for this: $OPT. sometimes this variable is empty, sometimes it contains -e 'ssh -p1234'. But when I try to use this variable bash tries to escape apostrophe like \'
Now my question is how can I put apostrophe in a variable? I have tried the following scenarios and the interpreted command is also shown:
"-e 'ssh -p1234'"    ->    -e ''\''ssh' '-p1024'\'''               (escapes apostrophe)
-e'ssh -p1234'        ->    -essh -p1024                         (ignores apostrophe)
-e"ssh -p1234"       ->    -essh -p1234                         (ignores apostrophe)
-e\"ssh\ -p1234\"    ->    '-e"ssh' '-p1024"'                   (escapes only quotation marks)
-e\'ssh\ -p1234\'     ->    '-e'\''ssh' '-p1024'\'''               (escapes only apostrophes)
-e\ ssh\\\ -p1234     ->   -e 'ssh\' -p1024                      (escapes backslashes)

I'm a few tries away from pulling out my hair, so any help is appreciated.

Awebb

Member

Registered: 2010-05-06

Posts: 6,688

Re: How to put apostrophe in variable

$ BLA="ssh -p 1234"
$ echo $BLA
ssh -p 1234
$ echo '$BLA'
$BLA
$ echo \'$BLA\'
'ssh -p 1234'

?

asaba90

Member

Registered: 2015-03-06

Posts: 7

Re: How to put apostrophe in variable

$ OPT="-e 'ssh -p1234'"
+ OPT='-e '\''ssh -p1024'\'''
$ echo $OPT
+ echo -e ''\''ssh' '-p1024'\'''
'ssh -p1024'

I want to have 2 different spaces in my variable. The first space should separate arguments, but the second one should not. You can see how bash interprets spaces in these examples.

dimich

Member

From: Kharkiv, Ukraine

Registered: 2009-11-03

Posts: 320

Re: How to put apostrophe in variable

Use quotes when variable is substituted with it's content:

$ OPT="-e 'ssh -p 1234'"
$ echo rsync "${OPT}"
rsync -e 'ssh -p 1234'

alphaniner

Member

From: Ancapistan

Registered: 2010-07-12

Posts: 2,810

Re: How to put apostrophe in variable

An array would also work provided it's quoted when used:

rsync_ssh_arg=('-e' 'ssh -p 1234')
rsync "${rsync_ssh_arg[@]}"

POC:

$ array=('e' 'ssh -p 1234')
$ touch "${array[@]}"
$ ls -l
-rw-r--r-- 1 a9 users 0 Mar  4 10:22 e
-rw-r--r-- 1 a9 users 0 Mar  4 10:22 'ssh -p 1024'
$ rm "${array[1]}"
$ ls -l
-rw-r--r-- 1 a9 users 0 Mar  4 10:22 e

The quotes around the array actually result in each indexed item being quoted, so touch/rm see index 1 as a single argument. I changed '-e' to 'e' to avoid the potentially confusing need to pass '--' to touch and rm.

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