I am trying to parse an RSS feed on the Linux command line which involves formatting the raw output from the feed with sed.
I currently use this command:
feedstail -u http://www.heise.de/newsticker/heise-atom.xml -r -i 60 -f "{published}> {title} {link}" | sed 's/^\(.\{3\}\)\(.\{13\}\)\(.\{6\}\)\(.\{3\}\)\(.*\)/\1\3\5/'
This gives me a number of feed items per line that look like this:
Sat 20:33 GMT> WhatsApp-Ausfall: Server-Probleme blockieren Messaging-Dienst http://www.heise.de/newsticker/meldung/WhatsApp-Ausfall-Server-Probleme-blockieren-Messaging-Dienst-2121664.html/from/atom10?wt_mc=rss.ho.beitrag.atom
Notice the long URL at the end. I want to shorten this to better fit on the command line. Therefore, I want to change my sed command to produce the following:
Sat 20:33 GMT> WhatsApp-Ausfall: Server-Probleme blockieren Messaging-Dienst http://www.heise.de/-2121664
That means cutting everything out of the URL except a dash and that seven digit number preceeding the ".html/blablabla" bit.
Currently my sed command only changes stuff in the date bit. It would have to leave the title and start or the URL alone and then cut stuff out of it until it reaches the seven digit number. It needs to preserve that and then cut everything after it out. Oh yeah, and we need to leave a dash right in front of that number too.
I have no idea how to do that and can't find the answer after hours of googling. Help?
EDIT:
This is the raw output of a line of feedstail -u http://www.heise.de/newsticker/heise-atom.xml -r -i 60 -f "{published}> {title} {link}", in case it helps:
Sat, 22 Feb 2014 20:33:00 GMT> WhatsApp-Ausfall: Server-Probleme blockieren Messaging-Dienst http://www.heise.de/newsticker/meldung/WhatsApp-Ausfall-Server-Probleme-blockieren-Messaging-Dienst-2121664.html/from/atom10?wt_mc=rss.ho.beitrag.atom
EDIT 2:
It seems I can only pipe that output into one command. Piping it through multiple ones seems to break things. I don't understand why ATM.
Unfortunately (for me), I could only think of solving this with extended regexp syntax (either -E or -r flag on different systems):
... | sed -E 's|(://[^/]+/).*(-[0-9]+)\.html/.*|\1\2|'
UPDATE: In basic regexp syntax, the best I can do is
... | sed 's|\(://[^/]*/\).*\(-[0-9][0-9]*\)\.html/.*|\1\2|'
The key to writing this sort of regular expression is to be very careful about what the boundaries of what you expect are, so as to avoid the random gunk that you want to get rid of causing you problems. Also, you should bear in mind that you can use characters other than / as part of a s operation's delimiters.
sed 's!\(http://www\.heise\.de/\)newsticker/meldung/[^./]*\(-[0-9]+\)\.html[^ ]*!\1\2!'
Be aware that getting the RE right can be quite tricky; assume you'll need to test it! (This is a key part of the “now you have two problems” quote; REs very easily become horrendous.)
Something like this maybe?
... | awk -F'[^0-9]*' '{print "http://www.heise.de/-"$2}'
This might work for you (GNU sed):
sed 's|\(//[^/]*/\).*\(-[0-9]\{7\}\).*|\1\2|' file
You can place the first sed command so:
feedstail -u http://www.heise.de/newsticker/heise-atom.xml -r -i 60 -f "{published}> {title} {link}" |
sed 's/^\(.\{3\}\)\(.\{13\}\)\(.\{6\}\)\(.\{3\}\)\(.*\)/\1\3\5/;s|\(//[^/]*/\).*\(-[0-9]\{7\}\).*|\1\2|'
Related
Information about the environment I am working in:
$ uname -a
AIX prd231 1 6 00C6B1F74C00
$ oslevel -s
6100-03-10-1119
Code Block A
( grep schdCycCleanup $DCCS_LOG_FILE | sed 's/[~]/ \
/g' | grep 'Move(s) Exist for cycle' | sed 's/[^0-9]*//g' ) > cycleA.txt
Code Block B
( grep schdCycCleanup $DCCS_LOG_FILE | sed 's/[~]/ \n/g' | grep 'Move(s) Exist for cycle' | sed 's/[^0-9]*//g' ) > cycleB.txt
I have two code blocks(shown above) that make use of sed to trim the input down to 6 digits but one command is behaving differently than I expected.
Sample of input for the two code blocks
Mar 25 14:06:16 prd231 ajbtux[33423660]: 20160325140616:~schd_cem_svr:1:0:SCHD-MSG-MOVEEXISTCYCLE:200705008:AUDIT:~schdCycCleanup - /apps/dccs/ajbtux/source/SCHD/schd_cycle_cleanup.c - line 341~ SCHD_CYCLE_CLEANUP - Move(s) Exist for cycle 389210~
I get the following output when the sample input above goes through the two code blocks.
cycleA.txt content
389210
cycleB.txt content
25140616231334236602016032514061610200705008341389210
I understand that my last piped sed command (sed 's/[^0-9]*//g') is deleting all characters other than numbers so I omitted it from the block codes and placed the output in two additional files. I get the following output.
cycleA1.txt content
SCHD_CYCLE_CLEANUP - Move(s) Exist for cycle 389210
cycleB1.txt content
Mar 25 15:27:58 prd231 ajbtux[33423660]: 20160325152758: nschd_cem_svr:1:0:SCHD-MSG-MOVEEXISTCYCLE:200705008:AUDIT: nschdCycCleanup - /apps/dccs/ajbtux/source/SCHD/schd_cycle_cleanup.c - line 341 n SCHD_CYCLE_CLEANUP - Move(s) Exist for cycle 389210 n
I can see that the first code block is removing every thing other that (SCHD_CYCLE_CLEANUP - Move(s) Exist for cycle 389210) and is using the tilde but the second code block is just replacing the tildes with the character n. I can also see that it is necessary in the first code block for a line break after this(sed 's/[~]/ ) and that is why I though having \n would simulate a line break but that is not the case. I think my different output results are because of the way regular expressions are being used. I have tried to look into regular expressions and searched about them on stackoverflow but did not obtain what I was looking for. Could someone explain how I can achieve the same result from code block B as code block A without having part of my code be on a second line?
Thank you in advance
This is an example of the XY problem (http://xyproblem.info/). You're asking for help to implement something that is the wrong solution to your problem. Why are you changing ~s to newlines, etc when all you need given your posted sample input and expected output is:
$ sed -n 's/.*schdCycCleanup.* \([0-9]*\).*/\1/p' file
389210
or:
$ awk -F'[ ~]' '/schdCycCleanup/{print $(NF-1)}' file
389210
If that's not all you need then please edit your question to clarify your requirements for WHAT you are trying to do (as opposed to HOW you are trying to do it) as your current approach is just wrong.
Etan Reisner's helpful answer explains the problem and offers a single-line solution based on an ANSI C-quoted string ($'...'), which is appropriate, given that you originally tagged your question bash.
(Ed Morton's helpful answer shows you how to bypass your problem altogether with a different approach that is both simpler and more efficient.)
However, it sounds like your shell is actually something different - presumably ksh88, an older version of the Korn shell that is the default sh on AIX 6.1 - in which such strings are not supported[1]
(ANSI C-quoted strings were introduced in ksh93, and are also supported not only in bash, but in zsh as well).
Thus, you have the following options:
With your current shell, you must stick with a two-line solution that contains an (\-escaped) actual newline, as in your code block A.
Note that $(printf '\n') to create a newline does not work, because command substitutions invariably trim all trailing newlines, resulting in the empty string in this case.
Use a more modern shell that supports ANSI C-quoted strings, and use Etan's answer. http://www.ibm.com/support/knowledgecenter/ssw_aix_61/com.ibm.aix.cmds3/ksh.htm tells me that ksh93 is available as an alternative shell on AIX 6.1, as /usr/bin/ksh93.
If feasible: install GNU sed, which natively understands escape sequences such as \n in replacement strings.
[1] As for what actually happens when you try echo 'foo~bar~baz' | sed $'s/[~]/\\\n/g' in a POSIX-like shell that does not support $'...': the $ is left as-is, because what follow is not a valid variable name, and sed ends up seeing literal $s/[~]/\\\n/g, where the $ is interpreted as a context address applying to the last input line - which doesn't make a difference here, because there is only 1 line. \\ is interpreted as plain \, and \n as plain n, effectively replacing ~ instances with literal \n sequences.
GNU sed handles \n in the replacement the way you expect.
OS X (and presumably BSD) sed does not. It treats it as a normal escaped character and just unescapes it to n. (Though I don't see this in the manual anywhere at the moment.)
You can use $'' quoting to use \n as a literal newline if you want though.
echo 'foo~bar~baz' | sed $'s/[~]/\\\n/g'
I have an old LaTeX document (with a lot of formatting commands) that I want to convert to the more modern LaTeX (I want to do the update for several reasons, not the least of which is to reduce the coupling between content and formatting). At any rate, the document has a lot of calls to the deprecated command \pmatrix{ .... } which I would like to replace with the new amsmath command \begin{pmatrix} ... \end{pmatrix}. I have been trying to use sed to do this conversion but I have never used it before and I am having trouble.
Here is a MWE
LaTeX input string
\pmatrix{0&0\cr \frac{1}{2}&0\cr 0&0\cr}\pmatrix{1&1\cr 1&1\cr 1&1\cr}
with the expected output
\begin{pmatrix}0&0\\ \frac{1}{2}&0\\ 0&0\end{pmatrix}\begin{pmatrix}1&1\\ 1&1\\ 1&1\end{pmatrix}
The commands that I have been trying to use are variants of the following
sed 's/\\pmatrix{\(.*\cr[ ]*\)}/\\begin{pmatrix}\1 \\end{pmatrix}/g' <$WORKING_FILE >$OUTPUT_FILE
but the closest output that I have been able to achieve is
\begin{pmatrix}0 & 0 \\ 0 & 0 \\ 0 & 0 \end{pmatrix}
I am pretty sure that the problem is related to having two calls to pmatrix side by side, but I am not sure how to modify the regex to make this work.
I have searched google, but being so new to regex, I just got confused by all of the variations out there and which to use, and how to properly format such a thing.
The following might work for you:
sed -re 's/(\\pmatrix)\{([^}]*)}/\\begin{pmatrix}\2\\end{pmatrix}/g' -e 's/\\cr/\\\\/g' -e 's/\\\\\\end/\\end/g' inputfile
This works by:
substituting \pmatrix{...} with `\begin{matrix}...\end{matrix}
substituting \cr with \\
handling \\\end to make it \end
EDIT: As per your update, you might be better off splitting the relevant parts using grep before piping to sed:
grep -oP '\\pmatrix.*?\\cr}' inputfile | sed -re 's/\\pmatrix\{(.*)}/\\begin{pmatrix}\1\\end{pmatrix}/g;s/\\cr/\\\\/g;s/\\\\\\end/\\end/g'
This might work for you (GNU sed):
sed -r 's/\\cr/\n/g;s/\\(pmatrix)\{([^\n]*)\n([^\n]*)\n([^\n]*)\n\}/\\begin{\1}\2\\\\ \3\\\\ \4\\end{\1}/g;s/\n/\\cr/g' file
Convert \\cr to newlines. Do a global substitution command. Then convert those newlines left back to \\cr's.
How could I make a separate sed script (let's call it script.sed) that would display only the changed lines without having to use the -n option while executing it? (Sorry for my English)
I have a file called data2.txt with digits and I need to change the lines ending with ".5" and print those changed lines out in the console.
I know how to do it with a single command (sed -n 's/.5$//gp' data2.txt), however our university professor requires us to do the same using sed -f script.sed data2.txt command.
Any ideas?
The following should work for your sed script:
s/.5$//gp
d
The -n option will suppress automatic printing of the line, the other way to do that is to use the d command. From man page:
d Delete pattern space. Start next cycle.
This works because the automatic printing of the line happens at the end of a cycle, and using the d command means you never reach the end of a cycle so no lines are printed automatically.
This might work for you (GNU sed):
#n
s/.5$//p
Save this to a file and run as:
sed -f file.sed file.txt
Why does GNU sed sometimes handle substitution with piped output into another sed instance differently than when multiple expressions are used with the same one?
Specifically, for msys/mingw sessions, in the /etc/profile script I have a series of manipulations that "rearrange" the order of the environment variable PATH and removes duplicate entries.
Take note that while normally sed treats each line of input seperately (and therfore can't easily substitute '\n' in the input stream, this sed statement does a substitution of ':' with '\n', so it still handles the entire input stream like one line (with '\n' characters in it). This behavior stays true for all sed expressions in the same instance of sed (basically until you redirect or pipe the output into another program).
Here's the obligatory specs:
Windows 7 Professional Service Pack 1
HP Pavilion dv7-6b78us
16 GB DDR3 RAM
MinGW-w64 (x86_64-w64-mingw32-gcc-4.7.1.2-release-win64-rubenvb) mounted on /mingw/
MSYS (20111123) mounted on / and on /usr/
$ uname -a="MINGW32_NT-6.1 CHRIV-L09 1.0.17(0.48/3/2) 2011-04-24 23:39 i686 Msys"
$ which sed="/bin/sed.exe" (it's part of MSYS)
$ sed --version="GNU sed version 4.2.1"
This is the contents of PATH before manipulation:
PATH='.:/usr/local/bin:/mingw/bin:/bin:/c/PHP:/c/Program Files (x86)/HP SimplePass 2011/x64:/c/Program Files (x86)/HP SimplePass 2011:/c/Windows/system32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0:/c/si:/c/android-sdk:/c/android-sdk/tools:/c/android-sdk/platform-tools:/c/Program Files (x86)/WinMerge:/c/ntp/bin:/c/GnuWin32/bin:/c/Program Files/MySQL/MySQL Server5.5/bin:/c/Program Files (x86)/WinSCP:/c/Program Files (x86)/Overlook Fing 2.1/bin:/c/Program Files/7-zip:.:/c/Program Files/TortoiseGit/bin:/c/Program Files (x86)/Git/bin:/c/VS10/VC/bin/x86_amd64:/c/VS10/VC/bin/amd64:/c/VS10/VC/bin'
This is an excerpt of /etc/profile (where I have begun the PATH manipulation):
set | grep --color=never ^PATH= | sed -e "s#^PATH=##" -e "s#'##g" \
-e "s/:/\n/g" -e "s#\n\(/[^\n]*tortoisegit[^\n]*\)#\nZ95-\1#ig" \
-e "s#\n\(/[a-z]/win\)#\nZ90-\1#ig" -e "s#\n\(/[a-z]/p\)#\nZ70-\1#ig" \
-e "s#\.\n#A10-.\n#g" -e "s#\n\(/usr/local/bin\)#\nA15-\1#ig" \
-e "s#\n\(/bin\)#\nA20-\1#ig" -e "s#\n\(/mingw/bin\)#\nA25-\1#ig" \
-e "s#\n\(/[a-z]/vs10/vc/bin\)#\nA40-\1#ig"
The last sed expression in that line basically looks for lines that begins with "/c/VS10/VC/bin" and prepends them with 'A40-' like this:
...
/c/si
A40-/c/VS10/VC/bin
A40-/c/VS10/VC/bin/amd64
A40-/c/VS10/VC/bin/x86_amd64
/c/GnuWin32/bin
...
I like my sed expressions to be flexible (path structures change), but I don't want it to match the lines that end with amd64 or x86_amd64 (those are going to have a different string prepended). So I change the last expression to:
-e "s#\n\(/[a-z]/vs10/vc/bin\)\n#\nA40-\1\n#ig"
This works:
...
/c/si
A40-/c/VS10/VC/bin
/c/VS10/VC/bin/amd64
/c/VS10/VC/bin/x86_amd64
/c/GnuWin32/bin
...
Then, (to match any "line" matching the pseudocode "/x/.../bin") I change the last expression to:
-e "s#\n\(/[a-z]/.*/bin\)\n#\nA40-\1\n#ig"
Which produces:
...
/c/si
/c/VS10/VC/bin
/c/VS10/VC/bin/amd64
/c/VS10/VC/bin/x86_amd64
/c/GnuWin32/bin
...
??? - sed didn't match any character ('.') any number of times ('*') in the middle of the line ???
But, if I pipe the output into a different instance of sed (and compensate for sed handling each "line" seperately) like this:
| sed -e "s#^\(/[a-z]/.*/bin\)$#A40-\1#ig"
I get:
sed: -e expression #1, char 30: unterminated `s' command
??? How is that unterminated? It's got all three '#' characters after the s, has the modifiers 'i' and 'g' after the third '#', and the entire expression is in double quotes ('"'). Also, there are no escapes ('\') immediately preceding the delimiters, and the delimiter is not a part of either the search or the replacement. Let's try a different delimiter than '#', like '~':
I use:
| sed -e "s~^(/[a-z]/.*/bin)$~A40-\1~ig"
and, I get:
...
/c/si
A40-/c/VS10/VC/bin
/c/VS10/VC/bin/amd64
/c/VS10/VC/bin/x86_amd64
A40-/c/GnuWin32/bin
...
And, that is correct! The only thing I changed was the delimeter from '#' to '~' and it worked ???
This is not (even close to) the first time that sed has produced unexplainable results for me.
Why, oh, why, is sed NOT matching syntax in an expression in the same instance, but IS matching when piped into another instance of sed?
And, why, oh, why, do I have to use a different delimeter when I do this (in order not to get an "unterminated 's' command"?
And the real reason I'm asking: Is this a bug in sed, OR, is it correct behavior that I don't understand (and if so, can someone explain why this behavior is correct)? I want to know if I'm doing it wrong, or if I need a different/better tool (or both, they don't have to be mutually exclusive).
I'll mark a response it as the answer if someone can either prove why this behavior is correct or if they can prove why it is a bug. I'll gladly accept any advice about other tools or different methods of using sed, but those won't answer the question.
I'm going to have to get better at other text processors (like awk, tr, etc.) because sed is costing me too much time with it's unexplainable results.
P.S. This is not the complete logic of my PATH manipulation. The complete logic also finishes prepending all the lines with values from 'A00-' to 'Z99-', then pipes that output into 'sort -u -f' and back into sed to remove those same prefixes on each line and to convert the lines ('\n') back into colons (':'). Then "export PATH='" is prepended to the single line and "'" is appended to it. Then that output is redirected into a temporary file. Next, that temporary file is sourced. And, finally, that temporary file is removed.
The /etc/profile script also displays the contents of PATH before and after sorting (in case it screwed up the path).
P.P.S. I'm sure there is a much better way to do this. It started as some very simple sed manipulations, and grew into the monster you see here. Even if there is a better way, I still need to know why sed is giving me these results.
sed -e "s#^\(/[a-z]/.*/bin\)$#A40-\1#ig"
is unterminated because the shell is trying to expand "$#A". Put your expressions in single quotes to avoid this.
The expression
-e "s#\n\(/[a-z]/.*/bin\)\n#\nA40-\1\n#ig"
fails, or doesn't do what you expect, because . matches the newline in a multi-line expression. Check your whole output, the A40- is at the very beginning. Change it to
-e "s#\n\(/[a-z]/[^\n]*/bin\)\n#\nA40-\1\n#ig"
and it might be more what you expect. This may very well be the case with most of your issues with multi-line modifications.
You can also put the statements, one per line, into a standalone file and invoke sed with sed -f editscript. It might make maintenance of this a bit easier.
I need to get a username from an Unix path with this format:
/home/users/myusername/project/number/files
I just want "myusername" I've been trying for almost a hour and I'm completely clueless.
Any idea?
Thanks!
Maybe just /home/users/([a-zA-Z0-9_\-]*)/.*?
Note that the critical part [a-zA-Z0-9_\-]* has to contain all valid characters for unix usernames. I took from here, that a username should only contain digits, characters, dashes and underscores.
Also note that the extracted username is not the whole matching, but the first group (indicated by (...)).
The best answer to this depends on what you are trying to achieve. If you want to know the user who owns that file then you can use the stat command, this unfortunately has slightly different syntax dependant on the operating system however the following two commands work
Max OS/X
stat -f '%Su' /home/users/myusername/project/number/files
Redhat/Fedora/Centos
stat -c '%U' /home/users/myusername/project/number/files
If you really do want the string following /home/users then the either of the Regexes provided above will do that, you could use that in a bash script as follows (Mac OS/X)
USERNAME=$(echo '/home/users/myusername/project/number/files' | \
sed -E -e 's!^/home/users/([^/]+)/.*$!\1!g')
Check http://rubular.com/r/84zwJmV62G. The first match, not the entire match, is the username.
in a bourne shell something like :
string="/home/users/STRINGWEWANT/some/subdir/here"
echo $string | awk -F\/ '{print $3}'
would be one option, assuming its always the third element of the path. There are more lightweight that use only the shell builtins :
echo ${x#*users/}
will strip out everything up to and including 'users/'
echo ${y%%/*}
Will strip out the remainder.
So to put it all together :
export path="/home/users/STRINGWEWABT/some/other/dirs"
export y=`echo ${path#*users/}` && echo ${y%%/*}
STRINGWEWABT
Also checkout the bash manpage and search for "Parameter Expansion"
(\/home\/users\/)([^\/]+)
The 2nd capture group (index 1) will be myusername