I am looking for a reliable method to replace a sequence of chars in a text file. I know that the file will always follow a specific format and that I need to replace a specific range of chars (ie start at char 20, replace the next 11 chars with '#')
I have found several examples using sed and awk which accomplish this on most files. However, the hangup in my case is that the range of chars in the file contain random gibberish chars include several NULL chars. This causes the file commands to stop processing.
I know that the simplest fix would be to go to the process that creates the file and not pad the file with NULL chars. However, the file is generated by a process buried within ancient COBOL running on a mainframe and any changes there require nearly an act of congress.
so, knowing that I am stuck with what I have, is there any way to manipulate the file, from the command line, that can successfully overwrite the NULL chars?
Thanks in advance.
GNU dd can do that
echo '###########'|dd of=FILENAME seek=20 bs=1 count=11 conv=notrunc
Make sure the echo command provides enough characters as input.
Related
I'm looking for a bit of help here. I'm a complete newbie!
I need to look in a file for a code matching the pattern A00000_00_A and append a count to it, so the first time it appears it is replaced with A00000_00_A_001, second time A00000_00_A_002 etc. The output needs to be written back to the same file. Each file only contains 1 code, but it appears multiple times.
After some digging I have found-
perl -pi -e 's/Q\d{4,5}'_'\d{2}_./$&.'_'.++$A /ge' /users/documents/*.xml
but the issue is the counter does not reset in each file.
That is, the output of the first file is say Q00390_01_A_1 to Q00390_01_A_7, while the second file is Q00391_01_A_8 to Q00391_01_A_10.
What I want is Q00390_01_A_1 to Q00390_01_A_7 in the first file and Q00391_01_A_1 to Q00391_01_A_2 in the second.
Does anyone have any idea on how to edit the above code to make it do that? I'm a total newbie so ideally an edit to what I have would be brilliant. Thanks
cd /users/documents/
for f in *.xml;do
perl -pi -e 's/facs=.(Q|M)\d{4,5}_\d{2}_\w/$&._.sprintf("%04d",++$A) /ge' $f
done
This matches the string facs= and any character, then "Q" or "M" followed by either four or five digits, then an underscore, then two digits, another underscore, and a word character. The entire match is then concatenated with an underscore and the value of $A zero padded to four digits.
As a result of using gmv on a large nested directory to flatten in, I have a number of duplicate files separated out and with the extensions "._1_" "._2_" etc ( .... ._n_ )
eg "a.pdf.\_1\_"
ie its
a(dot)pdf(dot)(back slash)1(back slash)
as opposed to
a(dot)pdf(dot)1
which I want to reduce it back to "a.pdf"
I tried something like
sed -i .bak "s|.\_1\_||" *
which is usually reliable and doesn't require escape characters. However its giving me
"error: illegal byte sequence"
Grateful for help to fix. This is on Mac OSX terminal. Ideally I'd like a generic solution to fix ._*_ forms where the * varies 1 to 9
There are two challenges here.
How to deal with the duplicate basename (The suffixes '1', '2', ... mostly like added to designate different sections of a single file - may be different pages a PDF, etc. Performing rename that will strip the files may cause some important files to disappear.
How to deal with the "error: illegal byte sequence" which indicate that some special characters (unicode) are part of the file name. Usually ASCII characters with value >= \0xc0, which can not be decoded according to the current local. The fact that the file names are escaped (as per OP "a.pdf.\_1\_" may hint at additional characters, not displayed (assuming this was not added by the OP).
Proposed solution is to rename the file, and place the 'sequence' part, that make the file unique BEFORE the extension, allowing the extension to be used to determine file type.
a.pdf.1 => a.1.pdf
The rename command to perform this task is:
rename 's/(.).pdf.(_._)/$1$2.pdf/' .pdf.__
Adjust the file name list as needed, and use -n to verify before running.
rename -n s/.\_1\_// *.*_1_
works (remove the -n once tested).
I have a huge text file with strings of a special format. How can i quickly create another file with only strings corresponding to my condition?
for example, file contents:
[2/Nov/2015][rule="myRule"]"GET
http://uselesssotialnetwork.com/picturewithcat.jpg"
[2/Nov/2015][rule="mySecondRule"]"GET
http://anotheruselesssotialnetwork.com/picturewithdog.jpg"
[2/Nov/2015][rule="myRule"]"GET
http://uselesssotialnetwork.com/picturewithzombie.jpg"
and i only need string with "myRule" and "cat"?
I think it should be perl, or bash, but it doesn't matter.
Thanks a lot, sorry for noob question.
Is it correct, that each entry is two lines long? Then you can use sed:
sed -n '/myRule/ {N }; /myRule.*cat/ {p}'
the first rule appends the nextline to patternspace when myRule matches
the second rule tries to match myRule followed by a cat in the patternspace , if found it prints patternspace
If your file is truly huge to the extent that it won't fit in memory (although files up to a few gigabytes are fine in modern computer systems) then the only way is to either change the record separator or to read the lines in pairs
This shows the first way, and assumes that the second line of every pair ends with a double quote followed by a newline
perl -ne'BEGIN{$/ = qq{"\n}} print if /myRule/ and /cat/' huge_file.txt
and this is the second
perl -ne'$_ .= <>; print if /myRule/ and /cat/' huge_file.txt
When given your sample data as input, both methods produce this output
[2/Nov/2015][rule="myRule"]"GET
http://uselesssotialnetwork.com/picturewithcat.jpg"
I have a rather tricky request...
We use a special application which is connected to a oracle database. For control reasons the application uses special characters which are defined by the application and saved in a long field of the database.
My task is to query the long field periodically and check for changes. To do that, I write the content by using a bash script in a file and compare the old and the new file with md5sum.
When there's a difference, I want to send the old file via mail. The problem is, that the old file contains these special characters and I don't know how to replace them with for example a string which describes them.
I tried to replace them on the basis of their ASCII code, but this didn't work. I've also tried to replace them by their appearance in the file. (They look like this: ^P ) This didn't work neither.
When viewing the file by text editor like nano the characters are visible like described above. But when using cat on the file, the content is only displayed until the first appearance of such a control character.
As far as I know there is know possibility to replace them while querying from the database because of the fact that the content is in a LONG field.
I hope you can help me.
Thank you in advance.
Marco
^P is the Control-P character, which is decimal 16 or hexadecimal 0x10, also known as the Data Link Escape (DLE) character in ASCII.
To replace all occurrences of 0x10 in a file with another string we can use our friend gsed:
gsed "s/\x10/Data Link Escape/g" yourfile.txt
This should replace all occurrences of characters containing the hex value 0x10 with the text string "Data Link Escape". You'll probably want to use a different string - this is just an example.
Depending on the system you're using you may be able to use the standard sed command if your version of sed recognizes the \xNN single-character escape codes. If there are multiple hex characters you need to replace you may want to create a file containing your sed commands, one for each hexadecmial character you need to replace, and tell sed or gsed to use the commands in the file - consult the sed or gsed man pages for how to do this.
Share and enjoy.
You can use xxd to change the string to its hex representation, then use xxd -r to convert back.
Or, you can use uuencode and uudecode.
One option is to run the file through cat -v. This replaces nonprinting characters with visible representations (using the ^ notation for control characters):
$ echo $'\x10\x12\x13\x14\x16' | cat -v
^P^R^S^T^V
So I have a strange question. I have written a script that re-formats data files. I basically create new files with the right column order, spacing, and such. I then unix2dos these files (the program I am formatting these files for is DIPS for windows, and I assume that the files should be ansi). When I go to open the files in the DIPS Program however an error occurs and the file won't open.
When I create the same kind of data file through the DIPS program and open it in note pad, it matches exactly with the data files I have created with my script.
On the other hand if I open the data files that I have created with my script in Kedit first, save them, and then open them in the DIPS program everything works.
My question is what could saving in Kedit possibly do that unix2dos does not?
(Also if I try using note pad or word pad to save instead of Kedit the file doesn't open in DIPS)
Here is what was created using the diff command in unix
"
1,16c1,16
* This file is generated by Dips for Windows.
* The following 2 lines are the Title of this file.
Cobre Panama
Drill Hole B11106-GT
Number of Traverses: 0
Global Orientation is:
DIP/DIPDIRECTION
0.000000 (Declination)
NO QUANTITY
Number of extra columns are: 0
--
* This file is generated by Dips for Windows.
* The following 2 lines are the Title of this file.
Cobre Panama
Drill Hole B11106-GT
Number of Traverses: 0
Global Orientation is:
DIP/DIPDIRECTION
0.000000 (Declination)
NO QUANTITY
Number of extra columns are: 0
18c18
--
440c440
--
442c442
-1
-1
"
Any help would be appreciated! Thanks!
Okay! Figured it out.
Simply when you unix2dos your file you do not strip any space characters in between the last letter in a line and the line break character. When saving in Kedit you do strip the spaces between the last letter in a line and the line break character.
In my script I had a poor programing practice in which I was writing a string like this;
echo "This is an example string " >> outfile.txt
The character count is 32, and if you could see the break line character (chr(10)) the line would read;
This is an example string
If you unix2dos outfile.txt the line looks the same as above but with a different break line character. However when you place the file into Kedit and save it, now the character count is 25 and the line looks like this;
This is an example string
This occurs because Kedit does not preserve spaces at the end of a line. It places the return or line break character at the last letter or "non space" character in a line.
So programs that read literal input like DIPS (i'm guessing) or more widely used AutoCAD scripting will have a real problem with extra spaces before the return character. Basically in AutoCAD scripting a space in a line is treated as a return character. So if you have ten extra spaces at the end of a line it's treated the same as ten returns instead of the one you probably intended.
OH and if this helped you out or though it was good please give me a vote up!
unix2dos converts the line-break characters at the end of each line, from unix line breaks (10) to dos line breaks (13, 10)
Kedit could possible change the encoding of the file (like from ansi to UTF-8)
You can change the encoding of a file with the iconv utility (on a linux box)