I'd like to:
unset myvarname*
where myvarname is a string and * is... well, you got it.
I tried
env | grep string | unset
But it doesn't work.
I'm into a script, and I don't want to start a new shell so no env -i or source something or leaving the reentering the shell
In the Bash shell, the ${!prefix@} parameter expansion generates all variables that start with prefix.
${!prefix@}Expands to the names of variables whose names begin with prefix [...] When @ is used and the expansion appears within double quotes, each variable name expands to a separate word.
This list can then be passed to unset:
unset "${!myvarname@}"
If it's the Bash shell, do:
unset $(compgen -v myvarname)
For example, show all variables in my current environment beginning with the letter 'S':
unset $(compgen -v S)
Output:
SAL_USE_VCLPLUGIN
SCREEN_NO
SECONDS
SESSION
SESSIONTYPE
SHELL
SHELLOPTS
SHLVL
SSH_AUTH_SOCK
If it's a POSIX shell, try something more generic:
unset $(env | sed -n 's/^\(S.*\)=.*/\1/p')
Or if GNU grep is available:
unset $(env | grep -o '^S[^=]*')
-v is for all shell variables (exported as well as local). -e is for exported/environment variables, so that's probably what the OP wants since they are using env. See unix.stackexchange.com/questions/151118/…
nn1=foo nn2=bar nn3=baz ; compgen -v n, but this does not nn1=foo nn2=bar nn3=baz ; compgen -e n. Please elaborate if there's more to it...Try this -
unset $(env | grep string |awk -F'=' '{print $1}')
Let say I have environment variable like -
printenv
string1=hello
string2=vipin
and when you will search with string grep will fetch both environment and fetch the name of environment variable and pass to unset command.
env | awk -F= '{print $1}' can give false-positive results when env values are multi-line strings. compgen -e returns only the env names