bash_aliases和awk的引号转义

Question

I'm trying to create an alias for a command to see the memory use,

ps -u user -o rss,command | grep -v peruser | awk '{sum+=$1} END {print sum/1024}'

but, the naive,

#.bash_aliases
alias totalmem='ps -u user -o rss,command | grep -v peruser | awk '{sum+=$1} END {print sum/1024}''

gives errors:

-bash: alias: END: not found
-bash: alias: {print: not found
-bash: alias: sum/1024}: not found

I've tried with double quotes,

totalmem ="ps ... |awk '{sum+=$1} END {print sum/1024}'" , or

totalmem ='ps ... |awk "{sum+=$1} END {print sum/1024}"' , escaping,

totalmem ='ps ... |awk \\'{sum+=$1} END {print sum/1024}\\'' , or escaping double quotes ... but I can't seem to make it work.

totalmem ='ps ... |awk \\"{sum+=$1} END {print sum/1024}\\"' ,

gives the error

awk: "{sum+=}
awk: ^ unterminated string

Any tips appreciated.

Answer 1

You can avoid quoting issues by using a shell function instead of an alias:

totalmem () {
  ps -u user -o rss,command | grep -v peruser | awk '{sum+=$1} END {print sum/1024}'
}

This is also more flexible, as you could allow totalmem to take arguments, such as a user name to pass to the -u option of ps , as in this example:

totalmem () {
  ps -u "$1" -o rss,command | grep -v peruser | awk '{sum+=$1} END {print sum/1024}'
}

Answer 2

You almost have it, the $ will be expanded in double-quotes, so that needs extra escaping:

alias totalmem='ps -u user -o rss,command | grep -v peruser | awk "{sum+=\$1} END {print sum/1024}"'

Or with the pattern inside awk as suggested by iiSeymour :

alias totalmem='ps -u user -o rss,command | awk "!/peruser/ {sum+=\$1} END {print sum/1024}"'

Answer 3

Like this:

alias totalmem='ps -u user -o rss,command | grep -v peruser | awk '\''{sum+=$1} END {print sum/1024}'\'

Explanation: you may use different kind of quotes for the same argument, like "I'm double-quoted"'and I am $HOME-less'-and-i-am-not-quoted . Hence if you need a single quote inside single quotes, you can add '\\'' which (1) terminates single quoting, (2) adds literal single quote with \\' , (3) starts single quoting again.

(Aliases of this size are something that's better done as functions).