The hexdump command converts any file to hex values.
But what if I have hex values and I want to reverse the process, is this possible?
There is a similar tool called xxd. If you run xxd with just a file name it dumps the data in a fairly standard hex dump format:
# xxd bdata
0000000: 0001 0203 0405
......
Now if you pipe the output back to xxd with the -r option and redirect that to a new file, you can convert the hex dump back to binary:
# xxd bdata | xxd -r >bdata2
# cmp bdata bdata2
# xxd bdata2
0000000: 0001 0203 0405
I've written a short AWK script which reverses hexdump -C output back to the
original data. Use like this:
reverse-hexdump.sh hex.txt > data
Handles '*' repeat markers and generating original data even if binary.
hexdump -C and reverse-hexdump.sh make a data round-trip pair. It is
available here:
GitHub reverse-hexdump repo
Direct to reverse-hexdump.sh
Restore file, given only the output of hexdump file
If you only have the output of hexdump file and want to restore the original file, first note that hexdump's default output depends on the endianness of the system you ran hexdump on!
If you have access to the system that created the dump, you can determinate its endianness using below command:
[[ "$(printf '\01\03' | hexdump)" == *0103* ]] && echo big || echo little
Reversing little-endian hexdump
This is the most common case. All x86/x64 systems are little-endian. If you don't know the endianness of the system that ran hexdump file, try this.
sed 's/ \(..\)\(..\)/ \2\1/g;$d' dump | xxd -r
The sed part converts hexdump's format into xxd's format, at least so far that xxd -r works.
Reversing big-endian hexdump
sed '$d' dump | xxd -r
Known Bugs (see comment section)
A trailing null byte is added if the original file was of odd length (e.g. 1, 3, 5, 7, ..., byte long).
Repeating sections of the original file are not restored correctly if they were hexdumped using a *.
You can check your dump for above problematic cases by running below command:
grep -qE '^\*|^[0-9a-f]*[13579bdf] *$' dump && echo bug || echo ok
Better alternative to create hexdumps in the first place
Besides the non-posix (and therefore not so portable) xxd there is od (octal dump) which should be available on all unix-like systems as it is specified by posix:
od -tx1 -An -v
Will print a hexadecimal dump, grouping digits as single bytes (-tx1), with no Address prefixes (-An, similar to xxd -p) and without abbreviating repeated sections as * (-v). You can reverse such a dump using xxd -r -p.
As someone who sucks at bash, I could not understand the examples already posted.
Here is what would have helped me when I was originally searching:
Take your text file "AYE.TXT" and convert it into a hex dump called "BEE.TXT"
xxd -p "AYE.TXT" > "BEE.TXT"
Take your hex dump file ("BEE.TXT") and covert it back to ascii file "CEE.TXT"
xxd -r -p "BEE.TXT" > "CEE.TXT"
Now that you have some simple working code, feel free to check out
"xxd -help" on the command line for an explanation of what all those flags do.
(That part is the easy part, the hard part is the specifics of the bash syntax)
There is a tonne of more elegant ways to get this done, but I've quickly hacked something together that Works for Me (tm) when regenerating a binary file from a hex dump generated by hexdump -C some_file.bin:
sed 's/\(.\{8\}\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\)/\1: \2\3 \4\5 \6\7 \8\9/g' some_file.hexdump | sed 's/\(.*\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\) \(..\) |/\1 \2\3 \4\5 \6\7 \8\9 /g' | sed 's/.$//g' | xxd -r > some_file.restored
Basically, uses 2 sed processeses, each handling it's part of each line. Ugly, but someone might find it useful.
If you don't have xxd, use hexdump, od, perl or python:
The following all give the same output:
# If you only have hexdump
hexdump -ve '1/1 "%.2x"' mybinaryfile > mydump
# This gives exactly the same output as:
xxd -p mybinaryfile > mydump
# Or, much slower:
od -v -t x1 -An < mybinaryfile | tr -d "\n " > mydump
# Or, the fastest:
perl -pe 'BEGIN{$/=\1e6} $_=unpack "H*"' < mybinaryfile > mydump
# Or, if you somehow have Python, and not Perl:
python -c "print(open('mybinaryfile','rb').read().hex())" > mydump
Then you can copy and paste, or pipe the output, and convert back with:
xxd -r -p mydump mybinaryfileagain
# Or
xxd -r -p < mydump > mybinaryfileagain
The hexdump command is available almost everywhere, and is usually part of the default busybox - if it's not linked, you can try running busybox hexdump or busybox xxd.
If xxd is not available to reverse the data, then you can try awk
The old days: Zmodem
In the old days we used to use X/Y/Zmodem which is available in the package lrzsz which can tolerate lossy comms - but it's a bidirectional protocol so the binaries need to be running at the same time and there needs to be bidirectional comms:
# Demo on local machine, using FIFOs
mkfifo /tmp/fifo-in
mkfifo /tmp/fifo-out
sz -b mybinaryfile > /tmp/fifo-out < /tmp/fifo-in
mkdir out; cd out
rz -b < /tmp/fifo-out > /tmp/fifo-in
Luckily, screen supports receiving Zmodem, so if you're in a screen session:
screen
telnet somehost
Then type Ctrl+A and : and then zmodem catch and Enter. Then inside the screen on the remote host, issue:
# sz -b mybinaryfile
Press Enter when you see the string starting with "!!!".
When you see "Transfer Complete", you may want to run reset if you want to continue the terminal session normally.
This program reverses hexdump -C output back to the original data.
Usage:
make
make test
./unhexdump -i inputfile -o outputfile
see https://github.com/zhouzq-thu/unhexdump!
i found more simple solution:
bin2hex
echo -n "abc" | hexdump -ve '1/1 "%02x"'
hex2bin
echo -n "616263" | grep -Eo ".{2}" | sed 's/\(.*\)/\\x\1/' | tr -d '\n' | xargs -0 echo -ne
I have an UTF-16 encoded file and I want replace UNIX line endings with Windows line endings. I don't want to touch anything else.
Is there a linux command line tool that can search for two bytes "0A 00" and replace it with four bytes "0D 00 0A 00"?
Perl to the rescue:
perl -we 'binmode STDIN, ":encoding(UTF-16le)";
binmode STDOUT, ":encoding(UTF-16le):crlf";
print while <STDIN>;
' < input.txt > output.txt
You may use unix2dos, but you have to convert the file to a 8-bit encoding before, and back to UTF-16 after. The obvious intermediate candidate is UTF-8:
$ cat in.txt | iconv -f UTF-16 -t UTF-8 | unix2dos | iconv -f UTF-8 -t UTF-16 > out.txt
You can wrap these three piped commands in a handy script, if you wish.
#/bin/sh
iconv -f UTF-16 -t UTF-8 | unix2dos | iconv -f UTF-8 -t UTF-16
unix2dos is what you're looking for. See its different options to find the one that's right for your UTF-16 encoding.
Solution:
perl -pe "BEGIN { binmode $_, ':raw:encoding(UTF-16LE)' for *STDIN, *STDOUT }; s/\n\0/\r\0\n\0/g;" < input.file > output.file
Credit to my coworker Manu and Stream-process UTF-16 file with BOM and Unix line endings in Windows perl
My system is SUSE Linux Enterprise Server 11.
I'm trying to convert a data from utf-8 format to iso useing "iconv"
$>file test.utf8
test.utf8: UTF-8 Unicode text, with very long lines
$>
$>file -i test.utf8
test.utf8: text/plain charset=utf-8
$>
$>iconv -f UTF-8 -t ISO-8859-1 test.utf8 > test.iso
iconv: test.utf8:20:105: cannot convert
Could you help me wit this?
Thanks.
Your input file contains characters that don't exist in Latin 1. You can use the -c option to skip them:
iconv -c -futf8 -tl1 test.utf8 > test.iso
Sometimes it's best to use both -c and //TRANSLIT, e.g.
$ cat rodriguez
Rodrı́guez
$ file rodriguez
rodriguez: UTF-8 Unicode text
$ iconv --unicode-subst="<U+%04X>" -f UTF-8 -t ISO-8859-1 rodriguez
Rodr<U+0131><U+0301>guez
$ iconv -f UTF-8 -t ISO-8859-1 rodriguez
Rodr
iconv: rodriguez:1:4: cannot convert
$ iconv -f UTF-8 -t ISO-8859-1//TRANSLIT rodriguez
Rodri
iconv: rodriguez:1:5: cannot convert
$ iconv -c -f UTF-8 -t ISO-8859-1 rodriguez
Rodrguez
$ iconv -c -f UTF-8 -t ISO-8859-1//TRANSLIT rodriguez
Rodriguez
Use //TRANSLIT parameter and the dummy characters will be put.
iconv -f UTF-8 -t ISO-8859-1//TRANSLIT test.utf8 > test.iso
I am dynamically writing to a file the input of a serial port, like so:
sudo cu -s 19200 -l /dev/ttyUSB0 > serialContent.json
But when I open it, it shows me a lot of diamond question marks:
������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������*#*1##*1*0*702442501#9##*1*0*702442501#9##
What I want to get is only this portion: *#*1##*1*0*702442501#9##*1*0*702442501#9##
When I open the file with vim I get a lot of ^# characters.
I tried to replace the characters using sed 's|[^#]||g' serialContent.json > serialContent2.json and sed 's|[�]||g' serialContent.json > serialContent2.json with no luck.
This is what I get with this command:
$ file -bi serialContent.json
application/octet-stream; charset=binary
What can I do to remove those marks? Thanks!
This is the replacement character shown when you have non-printable data.
To remove all non-printable characters, you can pipe it through tr -cd '[:print:]':
sudo cu -s 19200 -l /dev/ttyUSB0 | tr -cd '[:print:]' > serialContent.json
What's considered printable depends on your locale. You may want to export LC_ALL=C first to ensure consistent results across machines.
Hi I am trying to convert some log files from a Microsoft SQL server, but the files are encoded using UTf-16LE and iconv does not seem to be able to convert them.
I am doing:
iconv -f UTF-16LE -t UTF-8 <filename>
I also tried to delete any carriage returns from the end of the line if there are any, but that did not fix it either. If I save it using gedit that works, but this is not a viable solution since I have hundreds of those files.
EDIT: Please see the new answer for the missing option
I forgot the -o switch!
The final command is :
iconv -f UTF-16LE -t UTF-8 <filename> -o <new-filename>
The command you specified will output to stdout. You can either use the -o parameter, or redirect your output:
with -o:
iconv -f UTF-16LE -t UTF-8 infile -o outfile
with piping:
iconv -f UTF-16LE -t UTF-8 infile > outfile
Both will yield the desired result.
However some versions of iconv (v1 on macOS for example) do not support the -o parameter and you will see that the converted text is echoed to stdout. In that case, use the piping option.