Running shell command that has nested quotes via s

问题:

I have this following shell command:

ssh user@host "df | grep /dev/ | \
awk 'BEGIN{print "DISK", "%USAGE", "STATUS"} {split($5, a, "%"); \
var="GREEN"; print $1, $5, var}' | column -t"

I need to run this over ssh but I get syntax error due to the presence of nested double and single quotes.

I tried the escape characters for before the beginning and ending of the quotes but it did not solve the problem.

However, on local system running this will give the following output:

$ df | grep /dev/ | \
awk 'BEGIN{print "DISK", "%USAGE", "STATUS"} {split($5, a, "%"); \
var="GREEN"; print $1, $5, var}' | column -t
DISK       %USAGE  STATUS
/dev/sda1  95%     GREEN

回答1:

A quoted heredoc allows you to omit the outer quotes:

ssh user@host <<'END'
df | grep /dev/ | awk 'BEGIN{print "DISK", "%USAGE", "STATUS"} {split($5, a, "%"); var="GREEN"; print $1, $5, var}' | column -t
END

回答2:

This is the case where here document comes handy:

ssh -t -t user@host<<'EOF'
df | awk 'BEGIN{print "DISK", "%USAGE", "STATUS"} /dev/{split($5, a, "%"); var="GREEN"; print $1, $5, var}' | column -t
EOF

回答3:

It's much simpler to just run df | grep remotely, and process the output locally with awk:

ssh user@host 'df | grep /dev' | awk '
    BEGIN{print "DISK", "%USAGE", "STATUS"}
    {split($5, a, "%"); var="GREEN"; print $1, $5, var}' | column -t