insert line into a new file in linux using shell script

Question

I need to write shell script to create a new file and insert some stuffs into it. The problem is, using sed 'i/blablabla' command, it only works when there is at least one line existed in the file. What is the command to insert into a new file?

Thanks

do you actually need to edit the stream (do some find/replacement in the text) before you write it to the file? — kclair
– kclair, Commented Mar 12, 2012 at 18:41

Charles Duffy · Accepted Answer · 2012-03-12 18:31:42Z

2

echo 'new line' >file_name

Also, you can append to the end without using sed using the >> operator:

echo 'additional line' >>file_name

answered Mar 12, 2012 at 18:31

Charles Duffy

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2 Comments

ssb Over a year ago

Really appreciated. So sed could not be applied in this case?

Charles Duffy Over a year ago

sed could be used, but there's no need for it -- sed is for editing streams; editing implies starting with something and changing it; you're not doing that, so just using functionality built into the shell instead of starting a separate tool (such as sed) makes more sense.

aqn · Accepted Answer · 2012-03-12 21:33:09Z

1

More variants:

cat >>file_being_appended_to <<some_random_string
This is the first line
This is the second line and it has a variable in it; it's right here: $some_variable
some_random_string

cat >>file_being_appended_to <<'some_random_string'
This is the first line
This is the second line and it has a variable reference in it; it's right here: $some_variable,
but this variable reference is not expanded because the beginning delimiter string has single quotes around it.
some_random_string

answered Mar 12, 2012 at 21:33

aqn

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1 Comment

aqn Over a year ago

Use vi? :) Seriously, I think you meant "If i want to write a script to add a line to middle of file, what shoud i do???"?

(line_number=40; sed "$line_number,\$d" your_file; ((line_number--)); echo "stuff you want inserted";sed "1,${line_number}d" your_file) >your_new_file

The first sed prints out the first part of the file; the second sed prints out the second part of the file.

aqn · Accepted Answer · 2012-03-12 21:28:41Z

0

Other variants:

echo 'This is the first line
This is the second line.' >file

some_variable="some value"
echo "This is the first line
This is the second line and it has a variable in it; it's right here: $some_variable" >file

answered Mar 12, 2012 at 21:28

aqn

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