How to use variables in SED command (bash)

Question

I have these 3 sed commands:

sed -i '10,$s/-.*/-$LOWX:HIGHX+$HIGHX]/' plot.p
sed -i '11,$s/+.*/+$HIGHY]/' plot.p
sed -i '14,$s/+.*/+$HIGHY/' plot.p

It is supposed to go to the line denoted by the first value (ie 10, 11, 14) and replace text following the character specified (ie -, +).

Currently, my sed command doesn't recognize the variables ($LOWX, $HIGHX, and $HIGHY), and it just makes the replacement with the literal "$LOWX" for example.

How can I get my sed command to recognize the variables within it?

I saw other answers to similar questions saying to use double quotes but that causes my sed command to be misinterpreted so that it cannot run.

My output:

set xr[LOWX-$LOWX:HIGHX+$HIGHX]
set yr[0:HIGHY+$HIGHY]
set ytics 0,1,HIGHY+$HIGHY

Desired output:

set xr[LOWX-2:HIGHX+2]
set yr[0:HIGHY+1]
set ytics 0,1,HIGHY+1

jared_mamrot · Accepted Answer · 2022-02-21 04:04:12Z

1

Does this give you your desired output?

sed -i "10,\$s/-.*/-$LOWX:HIGHX+$HIGHX]/" plot.p
sed -i "11,\$s/+.*/+$HIGHY]/" plot.p
sed -i "14,\$s/+.*/+$HIGHY/" plot.p

answered Feb 21, 2022 at 4:04

jared_mamrot

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Verdigrass · Accepted Answer · 2022-02-21 04:15:51Z

1

Single quotes will work. Take mine as a quick reference:

LAUNCH_APP="./xxx/launch-app.sh"
OLD_PROXY="xx-proxy.uds"
num=$(sed -n "/$OLD_PROXY/=" "$LAUNCH_APP")
sed -i ''${num}'s/^/#/' "$LAUNCH_APP"

answered Feb 21, 2022 at 4:15

Verdigrass

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