Skipping the first line of file
You just made a typo in the last line of your awk script: It should read FNR instead of FR in the address:
This works here as expected.
With the typo, the address FR>1 does not match any of your data lines: FR is a constant and the condition FR>1 always false. That’s why you do not get any output.
There are several ways to skip the first line.
NR>1 < … ># For every record after the first. BEGIN < getline ># Only on the start, read the first line !var # If var is unset, set it and skip one line. FNR>1 < … ># For records after the first for every file listed. The variable NR means «Number of Record», and, assuming the default record delimiter (a newline) is in use, that is also the number of each line. The first line (in that case) is numbered 1 . If NR is greater than 1 , then what is executed inside the curly brace is executed only after the first line.
The variable FNR , instead, means the record number reset to zero for each file listed in the command line ( awk ‘script’ file1 file2 filen … ). Which is exactly equivalent to NR>1 but gets reset for each new file.
Trimming function
Additionally, you have a function definition for t(n,s) which aims (according to your comment) «to cut the number for 2 decimal places», but it doesn’t do that correctly.
In that function definition there is a command that finds the dot. It is assuming the dot is the decimal separator:
And then (as an string) cuts the string for the field two characters after the dot. That, for a number without exponent, works correctly to trim the decimals, but is the number is using an exponent, like 1.2345678e3 . It will be trimmed to 1.23 . That is, of course, not the same as the correct trimming to two decimals as 1234.56 .
To correctly trim the number, you must take the exponent into account. The int function does exactly that:
But you can better rely on the approximation that is applied to floats:
They are different in the amount of approximation (actually, the type) each do. The function using int rounds toward zero to the lower integer (for a positive number). For a number like 3.7 , it rounds down to 3 anyway, the error is 0.7 . The function with float rounds to the nearest integer. The maximum error is 0.5 . A number as above, like 3.7 , rounds to 4 , the error is only 0.3 . So, one is a round toward zero approximation, the other is a round to nearest integer. One could have a max error of 0.9 , the other of only 0.5 . The only estrange thing about the float approximation is that it sometimes 0.5 rounds up and sometimes 0.5 rounds down. That is intended to balance rounds up with rounds down.
It is clear that 0.1, 0.2, 0.3 and 0.4 should round down to 0.
That generates errors of 0.1, 0.2, 0.3, and 0.4.
Instead 0.9, 0.8. 0.7 and 0.6 round up to 1.
That generates error of -0.1, -0,2, -0.3, -0.4
All those errors (in average, for a random input) balance out.
But if we round 0.5 always up, it generates a constant error of 0.5.
To balance it out, once we round down, the next we round up.
Or, as it is usually written: round ties (0.5) to even.
printf '%s ' $l; echo; printf '%-3.0f ' $l; echo 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 Note that 0.5 rounds to 0 (down) and that 1.5 rounds to 2 (up)
Precision
You should use CONVFMT=»%.16g» as the format to convert floats.
An f format will trim off significant figures, like this:
Only two significant figures. Instead a g format:
Will keep the 9 significant figures (digits).
Filename
It is useful for awk commands that are applied to several files, like:
$ awk 'FNR>1' file1 file2 file3 To use FNR instead of NR, so the condition apply to each file in turn.
How to Skip 1st line of file — awk
where department is a header of column which is also counted although i used NR>1.. And how to add space or increase the width of all columns.. because it looks like above output.. but i wanna display it properly.. So any solution for this? Here is my input file
empid empname department 101 ayush sales 102 nidhi marketing 103 priyanka production 104 shyam sales 105 ami marketing 106 priti marketing 107 atuul sales 108 richa production 109 laxman production 110 ram production 2 Answers 2
Use GNU printf for proper tab-spaced formatting
You can use printf with width options as below example if printf «%3s»
From man awk , you can see more details:
width The field should be padded to this width. The field is normally padded with spaces. If the 0 flag has been used, it is padded with zeroes. .prec A number that specifies the precision to use when printing. For the %e, %E, %f and %F, formats, this specifies the number of digits you want printed to the right of the decimal point. For the %g, and %G formats, it specifies the maximum number of significant digits. For the %d, %o, %i, %u, %x, and %X formats, it specifies the minimum number of digits to print. For %s, it specifies the maximum number of characters from the string that should be printed. You can add the padding count as you need. For the input file you specified
$ awk 'NR>1 END >' file production 4 marketing 3 sales 3 Print file content without the first and last lines
Is there a simple way I can echo a file, skipping the first and last lines? I was looking at piping from head into tail , but for those it seems like I would have to know the total lines from the outset. I was also looking at split , but I don’t see a way to do it with that either.
5 Answers 5
Just with sed , without any pipes :
- 1 mean first line
- d mean delete
- ; is the separator for 2 commands
- $ mean last line
You don’t need to know the number of lines in advance. tail and head can take an offset from the beginning or end of the file respectively.
This pipe starts at the second line of the file (skipping the first line) and stops at the last but one (skipping the final line). To skip more than one line at the beginning or end, adjust the numbers accordingly.
tail -n +2 file.txt | head -n -1 doing it the other way round, works the same, of course:
head -n -1 file.txt | tail -n +2 I don’t know why, but head -n -1 removes the first AND the last line of my .txt file, on Ubuntu 14.04.2LTS.
Here is how to do it with awk :
x is advanced sed command, it switches current line with the previous one: current goes into the buffer and previous goes to the screen and so on while sed processing stream line by line (this is why the first line will be blank).
awk solution on each step (line) puts current line into the variable and starts printing it out only after the second line is passed by. Thus, we got shitfed sequence of lines on the screen from the second to the last but one. Last line is omitted becasue the line is in the variable and should be printed only on the next step, but all steps already run out and we never see the line on the screen.
perl -ne 'print $t if $.>2 ; $t=$_' file.txt $. stands for line number and $_ for current line.
perl -n is shortcut for while() structure and -e is for inline script.
Print a file, skipping the first X lines, in Bash [duplicate]
I have a very long file which I want to print, skipping the first 1,000,000 lines, for example. I looked into the cat man page, but I did not see any option to do this. I am looking for a command to do this or a simple Bash program.
13 Answers 13
You’ll need tail. Some examples:
If you really need to SKIP a particular number of «first» lines, use
That is, if you want to skip N lines, you start printing line N+1. Example:
If you want to just see the last so many lines, omit the «+»:
in centos 5.6 tail -n +1 shows the whole file and tail -n +2 skips first line. strange. The same for tail -c +
@JoelClark No, @NickSoft is right. On Ubuntu, it’s tail -n +
this must be outdated, but, tail -n+2 OR tail -n +2 works, as with all short commands using getopt, you can run the parameter right next to it’s switch, providing that the switch is the last in the group, obviously a command like tail -nv+2 would not work, it would have to be tail -vn+2. if you dont believe me try it yourself.
Easiest way I found to remove the first ten lines of a file:
In the general case where X is the number of initial lines to delete, credit to commenters and editors for this:
In the more general case, you’d have to use sed 1,Xd where X is the number of initial lines to delete, with X greater than 1.
This makes more sense if you don’t know how long the file is and don’t want to tell tail to print the last 100000000 lines.
@springloaded if you need to know the number of lines in the file, ‘wc -l’ will easily give it to you
If you have GNU tail available on your system, you can do the following:
tail -n +1000001 huge-file.log It’s the + character that does what you want. To quote from the man page:
If the first character of K (the number of bytes or lines) is a `+’, print beginning with the Kth item from the start of each file.
Thus, as noted in the comment, putting +1000001 starts printing with the first item after the first 1,000,000 lines.
@Lloeki Awesome! BSD head doesn’t support negative numbers like GNU does, so I assumed tail didn’t accept positives (with +) since that’s sort of the opposite. Anyway, thanks.
Also, to clarify this answer: tail -n +2 huge-file.log would skip first line, and pick up on line 2. So to skip the first line, use +2. @saipraneeth’s answer does a good job of exaplaining this.
If you want to skip first two line:
If you want to skip first x line:
This is somewhat misleading because someone may interpret (x+1) literally. For example, for x=2, they may type either (2+1) or even (3) , neither of which would work. A better way to write it might be: To skip the first X lines, with Y=X+1, use tail -n +Y
A less verbose version with AWK:
But I would recommend using integer numbers.
This version works in the Cygwin tools that come with Git for Windows, whereas tail and sed do not. For example git -c color.status=always status -sb | awk ‘NR > 1’ gives a nice minimal status report without any branch information, which is useful when your shell already shows branch info in your prompt. I assign that command to alias gs which is really easy to type.