How do I copy lines from one file to another in Linux without opening source and destination files and I need to exclude the comments when copying the lines.
I do not want to copy the comments in the first file and the files are in different locations
Assuming lines are commented with # at the very beginning of each line, the following should work:
grep -v "^#" path/to/input/file >path/to/output/file
(Note: This will either create a new output file or irreversibly overwrite the output file if it already exists)
Assuming comment lines in your file contain # at the beginning of each line, the following sed command will delete these lines:
$ sed '/^#/d' path/to/input-file > path/to/output-file
If your file can also contain lines with whitespace before the #, the following sed command will delete lines beginning with zero or more spaces or tabs (in any order), followed by a hash (#) character:
$ sed '/^[ \t]*#/d' path/to/input-file > path/to/output-file
If your file also contains lines containing code followed by a comment, the following sed command should work:
$ sed -e '/^[ \t]*#/d' -e 's/#.*$//' path/to/input-file > path/to/output-file
Related
I have output file that can be read by a visualizing tool, the problem is that at the beginning of each line there is one space. Because of this the visualizing tool isn't able to recognize the scripts and, hence crashing. When I manually remove the first column of spaces, it works fine. Is there a way to remove the 1st empty column of spaces using bash command
What I want is to remove the excess column of empty space like shown in this second image using a bash command
At present I use Vim editor to remove the 1st column manually. But I would like to do it using a bash command so that I can automate the process. My file is not just full of columns, it has some independent data line
Using cut or sed would be two simple solutions.
cut
cut -c2- file > file.cut && mv file.cut file
cut cannot modify a file, therefore you need to redirect its output to a different file and then overwrite the old file with the new file.
sed
sed -i 's/^.//' file
-i modifies the file in-place.
I would use
sed -ie 's/^ //' file
to just remove spaces (in case a line does not contain it)
I am looking for a way to achieve the following:
A certain directory contains 4 (config) files:
File1
File2
File3
File4
I want my bash script to read in each of the files, one by one. In each file, look for a certain line starting with "params: ". I want to comment out this line and then in the next line put "params: changed according to my will".
I know there are a lot of handy tools such as sed to aid with these kind of tasks. So I gave it a try:
sed -ri 's/params:/^\\\\*' File1.conf
sed -ri '/params:/params: changed according to my will' File1.conf
Questions: Does the first line really substitute the regex params: with \\ following a copy of the entire line in which params: was found? I am not sure I can use the * here.
Well, and how would I achieve that these commands are executed for all of the 4 files?
So this command will comment every line beggining by params: in you files, and append a text in the next line
sed -E -i 's/^(params:.*)$/\/\/\1\nYOUR NEW LINE HERE/g'
the pattern ^(params:.*)$ will match any whole line beggining by params:, and the parenthesis indicate that this is a capturing group.
Then, it is used in the second part of the sed command via \1, which is the reference of the first capturing group found. So you can see the second part comments the first line, add a line break and finally your text.
You can execute this for all your files simply by going sed -E -i 's/^(params:.*)$/\/\/\1\nYOUR NEW LINE HERE/g' file1 file2 file3 file4
Hope this helps!
You can do this:
for i in **conf
do
cp $i $i.bak
sed -i 's/\(params:\)\(.*\)$/#\1\2\n\1new value/'
done
With: \(params:\)\(.*\)
match params: and store it in `\1
match text following .*\: and store it in \2
Then create two lines:
The initial line commented: #\1\2\n
The new line with your wanted value: \1new value
This might work for you (GNU sed and parallel):
parallel --dry-run -q sed -i 's/^params:/#&/;T;aparams: bla bla' {} ::: file[1-4]
Run this in the desired directory and if the commands are correct remove the --dry-run option and run for real.
I have a UTF-8/no BOM file (converted from ISO-8859-1) that has 31214 lines. I have already run dos2unix on the file. When I open it in notepad++, I see a blank line underneath. When I remove this blank line, the line count reduces by one. I save it under a different name and when I tail the file, the prompt displays on the same line. From bash, how do I delete the blank line in the 1st file to produce the result displayed below in the 2nd file?
The goal is to do this from bash w/o manually deleting the line in notepad++
1st file:
[user#server]$ cat file1.txt | wc -l
31214
[user#server]$ tail file1.txt
T 31212 Data 20170517
[user#server]$
2nd file (edited with notepad++)
[user#server]$ cat file2.txt | wc -l
31213
[user#server]$ tail file2.txt
T 31212 Data 20170517[user#server]$
That's the trailing newline of the last line. Some editors allow you to go to the nonexisting "empty" line at the end, some don't show it. Again, some programs may allow you to remove the final newline, but note that e.g. POSIX in effect requires it to be there, and some standard utilities act oddly if it isn't present.
E.g. wc -l counts the number of newlines in the input file (printf "foo\nbar" | wc -l shows 1) so removing the final newline does decrease the line count.
Also, Bash prints the prompt wherever it was that the cursor was left on the screen, so if you print something that doesn't have the trailing newline, the prompt will be placed where the final incomplete line ended, as you saw.
There's no need to remove that final newline, just leave it there.
To remove the final newline character it is possible, as explained here, to use
sed -i '$ s/.$//' your.file
which will substitute nothing for the last character in the last line of the file (if you want to delete smth else from the end of the file you can replace the regex .$ with smth-else$). -i means ‘substitute in-place’ (in FreeBSD/MacOS you need to add an empty string as an argument: sed -i "" '$ s/.$//' your.file)
The file2.txt is missing a trailing newline.
Yes, a text file should end on a newline character.
Given that you do know that a trailing newline is missing, this command should be enough to correct the problem:
$ echo >> file2.txt
I used sed '/pattern/d' file > newfile to remove some lines in a text file, but there are lots of blank lines left in the new file.
How can I modify the command to avoid the blank lines?
sed '/pattern/d; /^$/d' file > newfile
There is some good discussion about regular expressions for deleting empty lines in a file in this Stack Overflow post
sed '/^$/d' file >newfile
...will do it for you.
The command that you use will delete all the lines you want to delete, but it leaves the blank lines that are already there in the original file in place. To delete these too, simply apply a second filter to the input:
$ sed -e '/pattern/d' -e '/^[:blank:]*$/d' <file >newfile
The second filter will remove lines that are empty, or that contains only whitespace characters (i.e., that are "blank" in their appearance).
I have this command sed -i 's/[A-Za-z]//g' file.txt that gets rid of any letters in my file but now have come to the realization that I need to be a little more steep with these errors.
How can I alter this command to Delete the line completely if there is letters in it?
000000asd000,12
000000000000,123
Would go to this
000000000000,123
sed -i '/[a-zA-Z]/d' file.txt
The /.../ command to match lines containing a letter, then d to delete the line.