Redis cli shell script unknown operand deleting keys with hex

Question

Created a shell script that deletes keys that matches a pattern using the following script:

host=${1:-}
port=${2:-6379}
database=${3:-0}
pattern=${4:-"Test"}

cursor=-1
keys=""

echo "Starting to delete"
while [ $cursor -ne 0 ]; do
  if [ $cursor -eq -1 ]
  then
    cursor=0
  fi

  reply=`redis-cli -h $host -p $port SCAN $cursor MATCH $pattern`
  cursor=`expr "$reply" : '\([0-9]*[0-9 ]\)'`
  keys=${reply##[0-9]*[0-9 ]}
  echo "$keys"
  redis-cli -h $host -p $port DEL $keys
done

This is working fine for keys that doesn't have hex in keys. But when keys with hex characters involved, encountered an unknown operand error message. Sample key:

\xac\xed\x00\x05t\x00\x15test

Need suggestions on how to escape these characters.

The same problem here: https://stackoverflow.com/questions/46854691/how-to-delete-redis-keys-with-special-characters

score 1 · Accepted Answer · answered Nov 05 '20 at 03:30

1

You should try to quote the keys

redis-cli -h $host -p $port DEL "$keys"

That should suffice. Without the quotes, the backslashes may be interpreted differently. It may also be necessary to double the backslashes. You could use sed for that.

redis-cli -h $host -p $port DEL `echo "$keys" | sed -e 's/\\/\\\\/'`

The shell is likely transforming "\x" into just "x".

answered Nov 05 '20 at 03:30

Alexis Wilke

2,697
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when using sed ��ttestERR wrong number of arguments for 'del' command – Anonymous Duck Nov 05 '20 at 03:36
You can try to run that `echo "$keys" | sed -e 's/\\/\\\\/'` on its own... to see that the output is correct. – Alexis Wilke Nov 05 '20 at 03:40
this is the output `��ttest`. Is it because of this weird characters? – Anonymous Duck Nov 05 '20 at 03:46
So the hex characters were already transformed to characters/bytes. I'm not too sure how you'd deal with that. – Alexis Wilke Nov 05 '20 at 03:49
1

Yes. I updated the question and added link to similar issue. Suggestion is to use different client. I'll try to python instead – Anonymous Duck Nov 05 '20 at 03:51
still accepted as an answer because the question is about hex and this answer provides solution for that scenario – Anonymous Duck Nov 05 '20 at 04:51

Redis cli shell script unknown operand deleting keys with hex

1 Answers1