A bit of background: sh -c expects a single string, which is interpreted as a command. Anything after that are positional parameters to that command. So by this way of quoting, sh -c gets passed two strings:

Code:

'sed -e 's/

and

Code:

//g''

The first is interpreted as a command:

Code:

sed -e s/

which is a call to sed with an unterminated substitute pattern s/ (s command) and therefore this will fail.


In the first case, instead of a space there is the letter t, so only one string gets passed to sh -c, namely:

Code:

'sed -e 's/t//g''

which gets interpreted as the following command:

Code:

sed -e s/t//g

which is a valid command.