Shell Programming and Scripting

Hi Guys,

I have a text where we used Ram in 10 times now I want replace all Ram words by Shyam word then how to do it.

Hi, try:

Code:

sed s,Ram,Shyam,g -i file.txt

hth

Thanks sea, please explain here how to work sed command, as you write I could not understand meaning of s, g, -i, please explain it, also I have study many tutorial links from Google but unable to use it, please enhance it or share any good link according your.

Hello aaditya321,

Please use code tags while using commands or codes in your posts. you can refer the forum rules as following link.
https://www.unix.com/misc.php?do=cfrules

For explaination part of command is as follows.

Code:

sed 's/source text/The text to be replaced with/g -i Input_file

Here s is used because we need to do substitute operation, /Ram/Shyam means to replace word Ram with Shyam, g means to do this subtitute operation globally else it will perform this substitute operation only at 1st match of the word, -i will edit the Input_file and save it too. You can refer the man sed page too for same.

Thanks,
R. Singh

Very nice explanation here, Thanks R. Singh, Please can you share any good link where we can read type of above explanation.

Thank you Aditya, you can refer man sed which is the best. Following links are also having good knowledge for sed too.
Hope this helps you.

Sed - An Introduction and Tutorial
sed

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Thanks,
R. Singh

s sed command: substitute
Ram regexp
Shyam replacement
g sed pattern flag: global substitution
-i sed command line option: "in place" editing

In other words, substitute every occurrence of Ram with Shyam and also change it in the file.

One problem could be that the mentioned sed command doesn't really ensure to match Ram as a single word, so it will also replace Ram in Ramesh, Rammstein and so on, too.

This awk might be more robust

Code:

awk '{ for (i=1;i<=NF;i++) if ($i == "Ram") { $i = "Shyam" }; print }' file

for (i=1;i<=NF;i++) in every line, parse every field
if ($i == "Ram") { $i = "Shyam" } if a field equals Ram, change that field to Shyam
print after all fields in a line are parsed (and potentially modified), print the whole line

Sed - An Introduction and Tutorial is pretty

Hope this helps.

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