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Which is the awk command to print all lines?
Everything is done using internal awk tools ( NR and FNR) apart from a single arithmetic comparison. I tested on a 50MB file with one million lines created with this command:
How to print all the lines except the last three lines?
If awk had push and pop operators for arrays, it would be easier. Or we could pre-calculate the number of lines and how far we actually want to go with $ ( ($ (wc -l < file) – 3)). This is relatively useless for streamed content but on a file, works pretty well: Using terdon’s benchmark we can actually see how these compare.
Are there any downsides to printing all the lines?
The immediate upsides are it doesn’t store all the content in memory and it shouldn’t cause buffering issues ( fflush () after printing if it does) but the downside here is it’s not simple to scale this up. If you want to skip the last 100 lines, you need 100 variables and 100 variable juggles.
How to add prefix to end of line?
Use the following commands to append some PREFIX to the beginning and some SUFFIX to the end of every line in a FILE: Cool Tip: You can also easily remove characters from the beginning or from the end of a line using cut command! Read more → Let’s say you have some file with multiple lines.
Can you use AWK to do the same thing?
The awk to do the same thing is very long-winded, see Marco’s answer. Maybe slightly off-topic, but I used the answer from belisarius to create my own variation of the above solution, that searches for the Nth entry, and returns that and the previous line.
How to skip first two fields in AWK?
You can use the awk command as follows. The syntax is as follows to skip first two fields and print the rest (thanks danliston ): awk ‘ { $1=””; $2=””; print}’ filename. To skip first three fields, enter: awk ‘ { $1=””; $2=””; $3=””; print}’ filename. You can specify the input field separator too.
How to save the output of this awk command to file?
> => This will redirect STDOUT to a file. If file not exists, it will create it. If file exists it will clear out (in effect) the content and will write new data to it
Why is$ 2 null in AWK Stack Exchange?
The input sent to awk will only ever have only one column of input, so $2 will always be null. where echo would instead be your “my command”… Thanks for contributing an answer to Unix & Linux Stack Exchange!