已经使用单引号和双引号时，如何为 awk 添加引号？

Question

I want to write an alias so that my squeue command outputs only the simulations that are running. For my squeue command, I've an alias in my.bashrc as follow

alias sq='squeue -u as1056 --format="%.18i %.36j %.8u %.2t %.10M %.10L %.6D %.6C %.12P %R"'

With this, I can output the running simulations as

sq | awk '$4 == "R" {print $0}'

This works as intended in the command line. I now want to add this command as an alias

alias sqrun='sq | awk "$4 == \"R\" {print $0}"'

As you can see, the single quotes are already exhausted after the equal to sign and hence, double quotes are needed after the awk command. However, to match the pattern in column 4, I need to specify another string. Since single quote and double quotes have already been used, I'm not sure how I can specify a string in this scenario. I tried escaping the double quotes using backslash but it throws error:

awk: cmd. line:1:  == "R" {print -bash}
awk: cmd. line:1:  ^ syntax error

So how should I specify an alias in such scenario?

Edit1: There's a dirty way of doing it by matching a simple R pattern across the sq command. The problem is that it often matches columns which contain the word "DRAINED". So I can use sed to delete such lines. So something like

sq | awk "/R/ {print $0}" | sed "/DRAINED/d"

won't run into the problem of having 3 quotes in the command. But I want to avoid this approach as it's not generic and may give erroneous results if there ever happens to be a column containing R and not containing the word "DRAINED".

PS: This is my first ever question on stackoverflow, so I'll appreciate your feedback if you notice any mistakes in the way I've asked this question!

Answer 1

you can chain single quoted sections by double quoting single quotes

alias sqrun='sq | awk '"'"' $4 == "R" {print $0} '"'"' '

added extra spaces for clarity but not needed. However these nested quotes can become really hard to read and probable not a good idea except only for trivial cases and throw away scripts.

Answer 2

The awk script contains $ and when you change the quotes around the awk script from ' to " , it makes bash treat them as variables to substitute. You have to also escape $ :

alias sqrun='sq | awk "\$4 == \"R\" {print \$0}"'

Answer 3

I would go with a simple:

alias sqrun='sq | awk '\''$4 == "R" {print $0}'\'

or with a function, like @DiegoTorresMilano suggested:

sqrun() { sq | awk '$4 == "R" {print $0}'; }

or if there are several aliases to define:

#!/bin/bash

while IFS='' read -r line
do
    alias "${line%%: *}=${line#*: }"
done <<'EOF'
sq: 'squeue -u as1056 --format="%.18i %.36j %.8u %.2t %.10M %.10L %.6D %.6C %.12P %R"'
squn: sq | awk '$4 == "R" {print $0}'
EOF