Delete First line of a file

Question

How can I delete the first line of a file and keep the changes?

I tried this but it erases the whole content of the file.

$sed 1d file.txt > file.txt

Answer 1

An alternative very lightweight option is just to 'tail' everything but the first line (this can be an easy way to remove file headers generally):

# -n +2 : start at line 2 of the file.
tail -n +2 file.txt > file.stdout

Following @Evan Teitelman, you can:

tail -n +2 file.txt | sponge file.txt

To avoid a temporary file. Another option might be:

echo "$(tail -n +2 file.txt)" > file.txt

And so forth. Testing last one:

[user@work ~]$ cat file.txt
line 1
line 2
line 3
line 4
line 5

[user@work ~]$ echo "$(tail -n +2 file.txt)" > file.txt
[user@work ~]$ cat file.txt
line 2
line 3
line 4
line 5
[user@work ~]$ 

Oops we lost a newline (per @1_CR comment below), try instead:

printf "%s\n\n" "$(tail -n +2 file.txt)" > file.txt

[user@work ~]$ cat file.txt
line 1
line 2
line 3
line 4
line 5

[user@work ~]$ printf '%s\n\n' "$(tail -n +2 file.txt)" > file.txt
[user@work ~]$ cat file.txt
line 2
line 3
line 4
line 5  

[user@work ~]$ 

Coming back to sed, try:

printf '%s\n\n' "$(sed '1d' file.txt)" > file.txt

or perhaps

echo -e "$(sed '1d' file.txt)\n" > file.txt

To avoid side effects.

Answer 2

The reason file.txt is empty after that command is the order in which the shell does things. The first thing that happens with that line is the redirection. The file "file.txt" is opened and truncated to 0 bytes. After that the sed command runs, but at the point the file is already empty.

There are a few options, most involve writing to a temporary file.

sed '1d' file.txt > tmpfile; mv tmpfile file.txt # POSIX
sed -i '1d' file.txt # GNU sed only, creates a temporary file

perl -ip -e '$_ = undef if $. == 1' file.txt # also creates a temporary file

Answer 3

This topic is interest, so I test the benchmark in 3 ways:

1. sed '1d' d.txt > tmp.txt
2. tail -n +2 d.txt > tmp.txt
3. sed -i '1d' d.txt

Note that target d.txt is 5.4GB file

Get the result :

---

run 1 : sed '1d' d.txt > r1.txt
14s
run 2 : tail -n +2 d.txt > r2.txt
20s
run 3 : sed -i '1d' d.txt
88s

---

Conclusion : It seems below be the quickest way:

sed '1d' file.txt > tmpfile; mv tmpfile file.txt

Answer 4

Also take a look at sponge from moreutils. sponge soaks in data from standard input until standard input's writing end closes before writing to a file. It is used like so:

sed '1d' file.txt | sponge file.txt

Answer 5

ex can be used for true in-place editing that does not involve a temp file

ex -c ':1d' -c ':wq' file.txt

Answer 6

You can use Vim in Ex mode:

ex -s -c '1d|x' file.txt

1. 1 find first line

2. d delete

3. x save and close

Answer 7

The shortest and simplest way to delete the first line from a file using sed is:

$ sed -i -n -e '2,$p' file.txt

Answer 8

Could use vim to do this:

vim -u NONE +'1d' +wq! /tmp/test.txt

Answer 9

You can try this:

awk 'NR>1 {print}' file.txt > file1.txt

Answer 10

This command will remove 1 line and save as "file.txt".

sed '1d' file.txt  > /tmp/file.txt && mv /tmp/file.txt file.txt || rm -f /tmp/file.txt

Answer 11

To delete a particular line in file:

1. Delete first line

   sed '1d' file
   

2. Delete first and third line

   sed '1d3d' file
   

To delete a charecter in a line

1. Delete First two charters in lin

   sed 's/^..//' file
   

2. Delete last two chrecters in line

   sed 's/..$//' file
   

3. Delete blank line

   sed '/^$/d' file