Re: Multi-line, double quoted string triggers history expansion on subsequent single-quoted commands it gets piped to

[Chet Ramey]

On 6/14/16 8:52 AM, Néstor Tejero wrote:

> When printing a multi-line string and piping to another command that uses
> single-quotes, Bash tries to perform history expansion:
> 
> echo "9
>> 10
>> 9
>> 11" | awk '!seen[$0]++'
> bash: !seen[$0]++': event not found

History expansion is explicitly line-oriented.  It doesn't know about shell
state, especially shell quoting state, that spans lines. It does know about
vaguely shell-like quoting that's common across a large set of Unix
utilities -- since the history and readline libraries are used outside the
shell --  and that a double quote introduces a quoted string in which
single quotes are not significant and don't inhibit history expansion.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/

Multi-line, double quoted string triggers history expansion on subsequent single-quoted commands it gets piped to

[Néstor Tejero]

Hello,
This is my system:

$ bash --version
GNU bash, version 4.3.11(1)-release (x86_64-pc-linux-gnu)

$ uname -a
Linux PCNTEJERO 3.19.0-51-generic #58~14.04.1-Ubuntu SMP Fri Feb 26
22:02:58 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
ntejero@PCNTEJERO: ~
$ cat /etc/*ease
DISTRIB_ID=LinuxMint
DISTRIB_RELEASE=17.3
DISTRIB_CODENAME=rosa
DISTRIB_DESCRIPTION="Linux Mint 17.3 Rosa"
NAME="Ubuntu"
VERSION="14.04.4 LTS, Trusty Tahr"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 14.04.4 LTS"
VERSION_ID="14.04"
HOME_URL="http://www.ubuntu.com/;
SUPPORT_URL="http://help.ubuntu.com/;
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/;
cat: /etc/upstream-release: Is a directory

Bash was installed through "apt-get install --only-upgrade bash"

The bug:
When printing a multi-line string and piping to another command that uses
single-quotes, Bash tries to perform history expansion:

echo "9
> 10
> 9
> 11" | awk '!seen[$0]++'
bash: !seen[$0]++': event not found
>

$ echo "9
> 10
> 11" | echo '!a'
bash: !a': event not found
>

Turning history off solves it, but anyway history expansion should not
occur within single-quotes. This does not happen in single lines:

$ printf "23\n24\n25" | echo '!a'
!a



Néstor