Single quotes would be better, you can still run into trouble with things getting parsed in double quotes. Edit: Example of this in zsh: # tiksi@layla 

Single quotes would be better, you can still run into trouble with things getting parsed in double quotes. Edit: Example of this in zsh: # tiksi@layla  ~  $ echo "http://example.com/uid=${thisisgone}-$(date)`pwd`\n\x00\x00nulletc\x0a" [09:38:50] http://example.com/uid=-Thu Apr 23 09:38:53 EDT 2015/home/tiksi nulletc # tiksi@layla  ~  $ curl -vv -s "http://example.com/uid=${thisisgone}-$(date)`pwd`\n\x00\x00nulletc\0xb" 2>&1|egrep GET [09:47:26] > GET /uid=-Thu Apr 23 09:47:41 EDT 2015/home/tiksi\n\x00\x00nulletc\0xb HTTP/1.1