How to change a word in a file with linux shell script

Question

I have a text file which have lots of lines I have a line in it which is: MyCar on

how can I turn my car off?

knittl · Accepted Answer · 2012-01-30 12:19:16Z

15

You could use sed:

sed -i 's/MyCar on/MyCar off/' path/to/file

answered Jan 30, 2012 at 12:19

knittl

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5 Comments

Behnam Safari Over a year ago

I read about sed but it was so hard to understand specially for a non-english man.

ghoti Over a year ago

@BehnamSafari, don't worry, it's hard to use for people who have English as their first language too. If you can speak line-noise, you're way ahead of the curve. (But seriously, sed is awesome.)

user5395338 Over a year ago

@ghoti: So true!. FWIW, your link is dead, but here's a great intro to sed.

ghoti Over a year ago

@Seamus, ah well, it's 8+ years since I posted that comment; one has to expect some churn. Thanks for posting that intro. Here's a link to the last capture of Towers of Hanoi

user5395338 Over a year ago

@ghoti: Yes - SO is becoming like a museum. I wonder what the average life expectancy of a URL is these days? The Towers of Hanoi was fascinating! I didn't know it was called by that name. I got one as a birthday gift when I was a small child - 5 or 6 yo I think... but it was made of wood instead of sed :)

Balaswamy Vaddeman · Accepted Answer · 2012-01-31 05:11:32Z

1

sed 's/MyCar on/MyCar off/' >filename

Comments

technosaurus · Accepted Answer · 2012-01-31 07:28:23Z

You can do this with shell only. This example uses an unnecessary case statement for this particular example, but I included it to show how you could incorporate multiple replacements. Although the code is larger than a sed 1-liner it is typically much faster since it uses only shell builtins (as much as 20x for small files).

REPLACEOLD="old"
WITHNEW="new"
FILE="tmpfile"
OUTPUT=""
while read LINE || [ "$LINE" ]; do
    case "$LINE" in
        *${REPLACEOLD}*)OUTPUT="${OUTPUT}${LINE//$REPLACEOLD/$WITHNEW}
";;
        *)OUTPUT="${OUTPUT}${LINE}
";;
    esac
done < "${FILE}"
printf "${OUTPUT}" > "${FILE}"

for the simple case one could omit the case statement:

while read LINE || [ "$LINE" ]; do
    OUTPUT="${OUTPUT}${LINE//$REPLACEOLD/$WITHNEW}
"; done < "${FILE}"
printf "${OUTPUT}" > "${FILE}"

Note: the ...|| [ "$LINE" ]... bit is to prevent losing the last line of a file that doesn't end in a new line (now you know at least one reasone why your text editor keeps adding those)

nathanchere · Accepted Answer · 2013-07-22 14:10:53Z

0

try this command when inside the file

:%s/old test/new text/g

edited Jul 22, 2013 at 14:10

nathanchere

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answered Jul 22, 2013 at 13:49

user2607061

1

Comments

jawad846 · Accepted Answer · 2021-01-28 07:08:53Z

0

Using sed with variables;

host=$(hostname)
se1=$(cat /opt/splunkforwarder/etc/system/local/server.conf | grep serverName)
sed -i "s/${se1}/serverName = ${host}/g"  /opt/splunkforwarder/etc/system/local/server.conf`

answered Jan 28, 2021 at 7:08

jawad846

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