I have a csv file and in a number of fields there are floating point numbers where the negative at the end of the number, I want these to be altered so as to have the minus/negative symbol at the front.
ie
23.4954-,23.12-
0.23-,16.5453
2495.1-,12,134-
I would like those to read
-23.4954,-23.12
-0.23,16.5453
-2495.1,-12,134
Out of 20 columns and a few thousand rows, there are probably about 80 instances per file, but it is a real pain to just go and replace them
I was hoping to use sed on the files to alter them if possible.
Any help is really appreciated.
Use the following approach:
sed -ri 's/([0-9.]+)-/-\1/g' filepath
-r (--regexp-extended) - allows using extended regular expressions rather than basic regular expressions
-i - option which allows to change file in place
You could use this sed command:
sed -E 's/([0-9.]+)-/-\1/g' file
This moves the - sign before a number composed of 0-9. characters.
Related
I have a plain text file:
line1_text
line2_text
I need to add a number of whitespaces between the two lines.
Adding 10 whitespaces is easy.
But say I need to add 10000 whitespaces, how would I achieve that using sed?
P.S. This is for experimental purposes
There undoubtedly is a sed method to do this but, since sed does not have any natural understanding of arithmetic, it is not a natural choice for this problem. By contrast, awk understands arithmetic and can readily, for example, print an empty line n times for any integer value of n.
As an example, consider this input file:
$ cat infile
line1_text
line2_text
This code will add as many blank lines as you like before any line that contains the string line2_text:
$ awk -v n=5 '/line2_text/{for (i=1;i<=n;i++)print""} 1' infile
line1_text
line2_text
If you want 10,000 blank lines instead of 5, then replace n=5 with n=10000.
How it works
-v n=5
This defines an awk variable n with value 5.
/line2_text/{for (i=1;i<=n;i++)print""}
Every time that a line matches the regex line2_text, then a for loop is performed with prints an empty line n times.
1
This is awk's shorthand for print-the-line and it causes every line from input to be printed to the output.
This might work for you (GNU sed):
sed -r '/line1_text/{x;s/.*/ /;:a;ta;s/ /&\n/10000;tb;s/^[^\n]*/&&/;ta;:b;s/\n.*//;x;G}' file
This appends the hold space to the first line. The hold space is manipulated to hold the required number of spaces by a looping mechanism based on powers of 2. This may produce more than necessary and the remainder are chopped off using a linefeed as a delimiter.
To change spaces to newlines, use:
sed -r '/line1_text/{x;s/.*/ /;:a;ta;s/ /\n&/10000;tb;s/^[^\n]*/&&/;ta;:b;s/\n.*//;s/ /\n/g;x;G}' file
In essence the same can be achieved using this (however it is very slow for large numbers):
sed -r '/line1_text/{x;:a;/ {20}/bb;s/^/ /;ta;:b;x;G}' file
I got 10,000 text files which I have to make changes.
First line on every file contains a url.
By mistake for few files url missking 'com'
eg:
1) http://www.supersonic./psychology
2) http://www.supersonic./social
3) http://www.supersonic.com/science
my task is to check and add 'com' if it is missing
eg:
1) http://www.supersonic.com/psychology
2) http://www.supersonic.com/social
3) http://www.supersonic.com/science
all urls are of same domain(supersonic.com)
can you suggest me any fast and easy approach ?
Tried this : replacing supersonic./ with supersonic.com
sed -e '1s/supersonic.//supersonic.com/' *
no change in the output.
Use -i to change the files instead of just outputting the changed lines.
Use a different delimiter than / if you want to use / in the regex (or use \/ in the regex).
Use \. to match a dot literally, . matches anything.
sed -i~ -e '1s=supersonic\./=supersonic.com/=' *
Some versions of sed don't support -i.
You are very close with your code, but you need to account for the trailing / char after the . char.
Assuming you are using a modern sed with the -i (inplace-edit) option you can do
sed -i '1s#supersonic\./#supersonic.com/#' *
Note that rather than have to escape / inside of the s/srchpat\/withSlash/replaceStr/', you can use another char after the the s command as the delimiter, here I use s#...#...#. If your search pattern had a # char, then you would have to use a different char.
Some older versions of sed need to you to escape the alternate delimiter at the first use, so
sed 's\#srchStr#ReplStr#' file
for those cases.
If you're using a sed that doesn't support the -i options, then
you'll need to loop on your file, and manage the tmp files, i.e.
for f in *.html ; do
sed '1s#supersonic\./#supersonic.com/#' "$f" > /tmp/"$f".fix \
&& /bin/mv /tmp/"$f".fix "$f"
done
Warning
But as you're talking about 10,000+files, you'll want to do some testing before using either of these solutions. Copy a good random set of those files to /tmp/mySedTest/ dir and run one of these solutions there to make sure there are no surprises.
And you're likely to blow out the cmd-line MAX_SIZE with 10,000+ files, so read about find and xargs. There are many posts here about [sed] find xargs. Check them out if needed.
IHTH
I'm running Windows and have the GnuWin32 toolkit, which includes sed. Specifically:
C:\TEMP>sed --version
GNU sed version 4.2.1
I have a text file with two sections: A fixed part I want to preserve, and a part that's appended after running a job.
In the file is a unique string that identifies the start of the part that's added, and I'd like to use Gnu sed to isolate only the part of the file that's before the unique string - i.e., so I can append different data to the fixed part each time the job is run.
I know I could keep the fixed portion in a separate file, but that adds complexity and it would be more elegant if I could just reuse the data at the start of the same file.
A long time ago I knew how to set up sed scripts, and I'm sure this can be done with sed, but I've slept since then. :)
Can you please describe how to use sed to display the lines of text in a file up to and not including a specific string?
Example:
line 1 of fixed portion
line 2 of fixed portion
unique string
line 1 of appended portion
line 2 of appended portion
line 3 of appended portion
What I'd like is to see as output:
line 1 of fixed portion
line 2 of fixed portion
I've gotten as far as:
sed -r -n -e "0,/unique string/p"
but that prints the unique string as well.
Thanks in advance.
-Noel
This should work for you:
sed -n '/unique string/q;p' file
It quits processing at unique string. Other lines get printed.
An alternative might be to use a range address like this:
sed -n '1,/unique string/{/unique string/!p}' file
Note that sed includes the range border. We need to exclude unique string from printing.
Furthermore I'm using the -n option which makes sed suppress the output of input lines by default.
One thing, if unique string can contain characters which are also syntax characters in the regex like ...
test*
... sed might not be the right tool for the job any more since it can only match regular expressions but not fixed strings.
In that case awk might be the tool of choice:
awk 'index("*unique string*"){exit}1' file
index("string") returns a non zero value (the position) if the string has been found. We cancel further processing of input lines in that case and don't print that line as well.
The trailing 1 always evaluates to true and makes awk print all the lines until the previous condition applies.
I want to insert a range of lines from a file, say something like 210,221r before the first occurrence of a pattern in a bunch of other files.
As I am clearly not a GNU sed expert, I cannot figure how to do this.
I tried
sed '0,/pattern/{210,221r file
}' bunch_of_files
But apparently file is read from line 210 to EOF.
Try this:
sed -r 's/(FIND_ME)/PUT_BEFORE\1/' test.text
-r enables extendend regular expressions
the string you are looking for ("FIND_ME") is inside parentheses, which creates a capture group
\1 puts the captured text into the replacement.
About your second question: You can read the replacement from a file like this*:
sed -r 's/(FIND_ME)/`cat REPLACEMENT.TXT`\1/' test.text
If replace special characters inside REPLACEMENT.TXT beforehand with sed you are golden.
*= this depends on your terminal emulator. It works in bash.
In https://stackoverflow.com/a/11246712/4328188 CodeGnome gave some "sed black magic" :
In order to insert text before a pattern, you need to swap the pattern space into the hold space before reading in the file. For example:
sed '/pattern/ {
h
r file
g
N
}' in
However, to read specific lines from file, one may have to use a two-calls solution similar to dummy's answer. I'd enjoy knowing of a one-call solution if it is possible though.
I have a list of usernames and i would like add possible combinations to it.
Example. Lets say this is the list I have
johna
maryb
charlesc
Is there is a way to use sed to edit it the way it looks like
ajohn
bmary
ccharles
And also
john_a
mary_b
charles_c
etc...
Can anyone assist me into getting the commands to do so, any explanation will be awesome as well. I would like to understand how it works if possible. I usually get confused when I see things like 's/\.(.*.... without knowing what some of those mean... anyway thanks in advance.
EDIT ... I change the username
sed s/\(user\)\(.\)/\2\1/
Breakdown:
sed s/string/replacement/ will replace all instances of string with replacement.
Then, string in that sed expression is \(user\)\(.\). This can be broken down into two
parts: \(user\) and \(.\). Each of these is a capture group - bracketed by \( \). That means that once we've matched something with them, we can reuse it in the replacement string.
\(user\) matches, surprisingly enough, the user part of the string. \(.\) matches any single character - that's what the . means. Then, you have two captured groups - user and a (or b or c).
The replacement part just uses these to recreate the pattern a little differently. \2\1 says "print the second capture group, then the first capture group". Which in this case, will print out auser - since we matched user and a with each group.
ex:
$ echo "usera
> userb
> userc" | sed "s/\(user\)\(.\)/\2\1/"
auser
buser
cuser
You can change the \2\1 to use any string you want - ie. \2_\1 will give a_user, b_user, c_user.
Also, in order to match any preceding string (not just "user"), just replace the \(user\) with \(.*\). Ex:
$ echo "marya
> johnb
> alfredc" | sed "s/\(.*\)\(.\)/\2\1/"
amary
bjohn
calfred
here's a partial answer to what is probably the easy part. To use sed to change usera to user_a you could use:
sed 's/user/user_/' temp
where temp is the name of the file that contains your initial list of usernames. How this works: It is finding the first instance of "user" on each line and replacing it with "user_"
Similarly for your dot example:
sed 's/user/user./' temp
will replace the first instance of "user" on each line with "user."
Sed does not offer non-greedy regex, so I suggest perl:
perl -pe 's/(.*?)(.)$/$2$1/g' file
ajohn
bmary
ccharles
perl -pe 's/(.*?)(.)$/$1_$2/g' file
john_a
mary_b
charles_c
That way you don't need to know the username before hand.
Simple solution using awk
awk '{a=$NF;$NF="";$0=a$0}1' FS="" OFS="" file
ajohn
bmary
ccharles
and
awk '{a=$NF;$NF="";$0=$0"_" a}1' FS="" OFS="" file
john_a
mary_b
charles_c
By setting FS to nothing, every letter is a field in awk. You can then easy manipulate it.
And no need to using capturing groups etc, just plain field swapping.
This might work for you (GNU sed):
sed -r 's/^([^_]*)_?(.)$/\2\1/' file
This matches any charactes other than underscores (in the first back reference (\1)), a possible underscore and the last character (in the second back reference (\2)) and swaps them around.