Is there a Shell Script program to delete one line of a file on the command line?

[kevdog]

Looking for a one line shell script on the command line I could use to remove a line in a config file (for example the first or last line or line that contains xxxxx). Here are the examples Ive found thus far. Any better methods?




awk 'NR!=4' file1 > file2

cp /etc/apt/sources.list /etc/apt/sources.list_backup
grep -v “line you want to remove” /etc/apt/sources.list_backup > /etc/apt/sources.list

[ghostdog74]

if they suit your purpose, then use them.
other method


head -3 file > newfile
more +5 file >> newfile


using sed


sed '4d' file

[erginemr]

Hi kevdog,

I think, your solution:

grep -v "line you want to remove" /etc/apt/sources.list_backup > /etc/apt/sources.list
is the most elegant way to do it.

Alternatively, you can use:

sed "/line you want to remove/d" /etc/apt/sources.list_backup > /etc/apt/sources.list
Kindly see the attached example...

[kevdog]

Just for my reference -- there is no way to avoid use of a temporary file (at least specifying one on the command line -- what happens internally within a buffer is different) other than with something similar to

sed '4d' file


Im not familar with the +5 part of this command:
more +5 file >> newfile

I read the man pages but they dont list this as an option. What exactly does this do?

[scruff]

GNU sed includes a -i option for "inline" edits. No need for a temp backup file :)

[kevdog]

So it would be something like this??:

sed -i "/line you want to remove/d" /etc/apt/sources.list

So hence the sources.list would be the same as the original, minus the line you removed?

[scruff]

Yes that is correct.

[ghostdog74]

I read the man pages but they dont list this as an option. What exactly does this do?

please read the man page again. you should see +num
it just simply means start from that line number (num)

[Roguebantha]

I accomplished deleting the last line of a file like this:
$cp Example1 ./tmp
$head --lines=-1 tmp > Example1

In which running head --lines=-1 shows all of the lines except the last one.

[Bachstelze]

GNU sed includes a -i option for "inline" edits. No need for a temp backup file :)

And even without GNU sed, the same thing can be achieved with ed (this is why POSIX sed does not include a similar functionality: it would be redundant since it's already in ed).

[nothingspecial]

Old thread.

Closed.