I saw following command
echo "haha" | mutt -s "test" -- $myemail
it will send an email with subject "test" and content "haha" to my email address. However, I can't figure what is -- for. I check both manpage and try a couple of experiments. But it's still puzzling for me.
Anyone has some clue?
Thanks
-- in many applications says "there are no more command line options, treat everything past this point as raw text on the command line."
In your example, you can probably omit and wrap the email in quotes (which also may not be strictly necessary).
echo "haha" | mutt -s "test" "myemail#gmail.com"
The -- helps if there's something odd expected afterwards, for example:
echo "haha" | mult -s "test" -- -foo#bar.com
without -- the parser library might consider -foo to be a command line option, but with it, it considers it just some word on the command line.
It means that there are no other options listed on the command line.
Related
So I've done some Google searching and this is something that has very little knowledge out there. What would be an effective and foolproof way of detecting whether X11 or Wayland is in use, preferrably at compile-time and with CMake? I need to apply this to a C++ project of mine.
The accepted answer is very inaccurate and dangerous. It just runs loginctl to dump a large list of user-sessions and greps every line with a username or other string that matches the current user's name, which can lead to false positives and multiple matching lines. Calling whoami is also wasteful. So it's harmful, and inaccurate.
Here's a much better way to get the user's session details, by querying your exact username's details and grabbing their 1st session scope's id.
This is a Bash/ZSH-compatible one-liner solution:
if [ "$(loginctl show-session $(loginctl user-status $USER | grep -E -m 1 'session-[0-9]+\.scope' | sed -E 's/^.*?session-([0-9]+)\.scope.*$/\1/') -p Type | grep -ic "wayland")" -ge 1 ]; then
echo "Wayland!"
else
echo "X11"
fi
I really wish that loginctl had a "list all sessions just for a specific user", but it doesn't, so we have to resort to these tricks. At least my trick is a LOT more robust and should always work!
I assume you want to evaluate the display server during compile time, when calling CMake, instead of for every compilation. That's how CMake works and hot it should be used. One downside is, that you have to re-run CMake for every changed display server.
There is currently no default way to detect the running display server. Similar, there is no default code snippet to evaluate the display server by CMake. Just pick one way of detecting the display server that manually works for you or your environment respectively.
Call this code from CMake and store the result in a variable and use it for your C++ code.
For example loginctl show-session $(loginctl | grep $(whoami) | awk '{print $1}') -p Type works for me. The resulting CMake check is
execute_process(
"loginctl show-session $(loginctl | grep $(whoami) | awk '{print $1}') -p Type"
OUTPUT_VARIABLE result_display_server)
if ("${resulting_display_server}" EQUALS "Type=x11")
set(display_server_x11 TRUE)
else()
set(display_server_x11 FALSE)
endif()
Probably you have to fiddle around with the condition and check for Type=wayland or similar to get it properly working in your environment.
You can use display_server_x11 and write it into a config.h file to use it within C++ code.
This seems like a relatively basic question, but I can't find it anywhere after an hour of searching. Many (there are a lot!) of the similar questions do not seem to hit the point.
I am writing a script ("vims") to use vim in a sed-like mode (so I can call normal vim commands on a stream input without actually opening vim), so I need to pass each argument to vim with a "-c" flag prepended to it. There are also many characters that need to be escaped (I need to pass regex expressions), so some of the usual methods on SO do not work.
Basically, when I write:
cat myfile.txt | vims ':%g/foo/exe "norm yyPImyfile: \<esc>\$dF,"' ':3p'
which are two command-line vim arguments to run on stdout,
I need these two single-quoted arguments to be passed exactly the way they are to my function vims(), which then tags each of them with a -c flag, so they are interpreted as commands in vim.
Here's what I've tried so far:
vims() {
vim - -nes -u NONE -c '$1' -c ':q!' | tail -n +2
}
This seems to work perfectly for a single command. No characters get escaped, and the "-c" flag is there.
Then, using the oft-duplicated question-answer, the "$#" trick, I tried:
vims() {
vim - -nes -u NONE $(for arg in "$#"; do echo -n " -c $arg "; done) -c ':q!' | tail -n +2
}
This seems to break the spaces within each string I pass it, so does not work. I also tried a few variations of the printf command, as suggested in other questions, but this has weird interactions with the vim command sequences. I've tried many other different backslash-quote-combinations in a perpetual edit-test loop, but have always found a quirk in my method.
What is the command sequence I am missing?
Add all the arguments to an array one at a time, then pass the entire array to vim with proper quoting to ensure whitespace is correctly preserved.
vims() {
local args=()
while (($# > 0)); do
args+=(-c "$1")
shift
done
vim - -nes -u NONE "${args[#]}" -c ':q!' | tail -n +2
}
As a rule of thumb, if you find yourself trying to escape things, add backslashes, use printf, etc., you are likely going down the wrong path. Careful use of quoting and arrays will cover most scenarios.
Can a bash/shell expert help me in this? Each time I use PDF to split large pdf file (say its name is X.pdf) into separate pages, where each page is one pdf file, it creates files with this pattern
"X 1.pdf"
"X 2.pdf"
"X 3.pdf" etc...
The file name "X" above is the original file name, which can be anything. It then adds one space after the name, then the page number. Page numbers always start from 1 and up to how many pages. There is no option in adobe PDF to change this.
I need to run a shell command to simply remove/strip out all the "X " part, and just leave the digits, like this
1.pdf
2.pdf
3.pdf
....
100.pdf ...etc..
Not being good in pattern matching, not sure what regular expression I need.
I know I need something like
for i in *.pdf; do mv "$i$" ........; done
And it is the ....... part I do not know how to do.
This only needs to run on Linux/Unix system.
Use sed..
for i in *.pdf; do mv "$i" $(sed 's/.*[[:blank:]]//' <<< "$i"); done
And it would be simple through rename
rename 's/.*\s//' *.pdf
You can remove everything up to (including) the last space in the variable with this:
${i##* }
That's "star space" after the double hash, meaning "anything followed by space". ${i#* } would remove up to the first space.
So run this to check:
for i in *.pdf; do echo mv -i -- "$i" "${i##* }" ; done
and remove the echo if it looks good. The -i suggested by Gordon Davisson will prompt you before overwriting, and -- signifies end of options, which prevents things from blowing up if you ever have filenames starting with -.
If you just want to do bulk renaming of files (or directories) and don't mind using external tools, then here's mine: rnm
The command to do what you want would be:
rnm -rs '/.*\s//' *.pdf
.*\s selects the part before (and with) the last white space and replaces it with empty string.
Note:
It doesn't overwrite any existing files (throws warning if it finds an existing file with the target name).
And this operation is failsafe. You can get back the changes made by last rnm command with rnm -u.
Here's a list of documents for rnm.
EDIT: I am using Cygwin. I am unsure whether this is of relevance and it was a detail I missed during writing this question.
EDIT2: Have tried replacing the "TAB" char people pointed out with the RegEx \s which covers spacing chars (spaces and tabs primarily) and this did not affect the expression at all, meaning that it is not the tabs causing the issue, especially since the expression runs once without errors anyway.
So far this script has been causing me a ton of trouble.
I DID have an issue before but I resolved that while I was writing a question here (lucky imo) but this one I've been stuck on for at least an hour now and I've tried varying solutions, none of which actually work or told me something I didn't already try.
I have a rather cool seeming FTP log fetcher script and part of this script replaces the 600MB of errors in this logfile to nothing, essentially removing them. Unfortunately this script also gets rid of parts of other errors too, so I've had to edit it. This is where I'm getting stuck.
Through base research I managed to find out that sed could do what I want, and through three hours of playing so far it does most of what I tell it to, minus one thing. One, and ONLY one, of the sed statements I have built only replaces the first instance of the string I've given it despite having the g modifier attached to the end.
I am working with a test script right now as to avoid potential permanent damage to my original FTP script, and the test script copies over an example file with a few of the errors I need replacing.
Walkthrough of the scripts INTENDED behaviour before showing:
1. Sets a prefix which happens on ALL lines in the file, pretty important part of the script.
2. Copies the example file to a file named test2.log
3. Replace all instances of the UNIX newline char \n with [loll] (first thing that came to my mind)
4. Remove all instances of battle error type 1 and 2.
5. Return all [loll] strings with the UNIX \n for newlines, therefore returning the logfile to its original state minus the errors.
Script:
#DTP="\[([0-9]+-[0-9]+-[0-9]+-[0-9]+|latest)\.log\] \[[0-9]+:[0-9]+:[0-9]+\] \[Server thread/(INFO|WARN)\]: "
echo "${DTP}"
DTP1="\[[0-9]*:[0-9]*:[0-9]*\]\s\[Server\sThread\/\(WARN\|INFO\)\]:\s"
DTP="\[loll\]\[[0-9]*:[0-9]*:[0-9]*\]\s\[Server\sThread\/\(WARN\|INFO\)\]:\s"
echo "${DTP}"
echo "1"
cp test.log test2.log
#cat test.log >test2.log
sed -i ':a;N;$!ba;s/\n/\[loll\]/g' test2.log #| egrep -i "" >test2.log
sed -i 's/'${DTP1}'Caught error in battle. Continuing...'${DTP}'java.lang.NullPointerException'${DTP}' at com.pixelmonmod.pixelmon.battles.controller.participants.PixelmonWrapper.useAttack(PixelmonWrapper.java:173)'${DTP}' at com.pixelmonmod.pixelmon.battles.controller.participants.PixelmonWrapper.takeTurn(PixelmonWrapper.java:330)'${DTP}' at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.takeTurn(BattleControllerBase.java:276)'${DTP}' at com.pixelmonmod.pixelmon.battles.controller.BattleControllerBase.update(BattleControllerBase.java:157)'${DTP}' at com.pixelmonmod.pixelmon.battles.BattleRegistry.updateBattles(BattleRegistry.java:63)'${DTP}' at com.pixelmonmod.pixelmon.battles.BattleTickHandler.tickStart(BattleTickHandler.java:12)'${DTP}' at cpw.mods.fml.common.eventhandler.ASMEventHandler_20_BattleTickHandler_tickStart_WorldTickEvent.invoke(.dynamic)'${DTP}' at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:51)'${DTP}' at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:122)'${DTP}' at cpw.mods.fml.common.FMLCommonHandler.onPostWorldTick(FMLCommonHandler.java:255)'${DTP}' at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:929)'${DTP}' at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:429)'${DTP}' at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:776)'${DTP}' at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:639)'${DTP}' at java.lang.Thread.run(Thread.java:745)//gI' test2.log
echo "2"
sed -i 's/'${DTP1}'Caught error in battle. Continuing...'${DTP}'java.lang.NullPointerException\[loll\]//gI' test2.log
echo "3"
sed -i 's/\[loll\]/\n/g' test2.log
I've set them to also run case insensitive checks on the provided strings as sometimes I write with all lower case, however for most of this I copied and pasted it directly.
Sample input:
http://pastebin.com/3KPB33X2
Outputs:
Expected:
meow
Test message
WOOF MEOWLOL
Actual: http://pastebin.com/pnvDwkxz
It's been killing my mind for a while now because I had this issue even before the other one, except I barely noticed it. I can't find any predictable behaviour in the script, and as far as I am aware it SHOULD be working perfectly fine and giving me the output I expect.
Any help would be appreciated, because as soon as I can get this bug sorted out I'll be able to enter in the rest of the script and replace this with the existing battle-error replacement script in my log-fetcher.
Knowing me it's something small and stupid but I've tried literally everything I came across, including adding the :a;N;$!ba; to the start of the bit which isn't working properly (and realising that failed horribly).
Thanks.
~BAI1
Are you looking for something like this:
sed -n ':a;s/\[.*Server thread\/\(INFO\|WARN\).*//i;/^$/!p;n;b a' battle.log
I wrote a short bash script that is supposed to strip the leading tabs/spaces from a string:
#!/bin/bash
RGX='s/^[ \t]*//'
SED="sed '$RGX'"
echo " string" | $SED
It works from the command line, but the script gets this error:
sed: -e expression #1, char 1: unknown command: `''
My guess is that something is wrong with the quotes, but I'm not sure what.
Putting commands into variables and getting them back out intact is hard, because quoting doesn't work the way you expect (see BashFAQ #050, "I'm trying to put a command in a variable, but the complex cases always fail!"). There are several ways to deal with this:
1) Don't do it unless you really need to. Seriously, unless you have a good reason to put your command in a variable first, just execute it and don't deal with this messiness.
2) Don't use eval unless you really really really need to. eval has a well-deserved reputation as a source of nasty and obscure bugs. They can be avoided if you understand them well enough and take the necessary precautions to avert them, but this should really be a last resort.
3) If you really must define a command at one point and use it later, either define it as a function or an array. Here's how to do it with a function:
RGX='s/^[ \t]*//'
SEDCMD() { sed "$RGX"; }
echo " string" | SEDCMD
Here's the array version:
RGX='s/^[ \t]*//'
SEDCMD=(sed "$RGX")
echo " string" | "${SEDCMD[#]}"
The idiom "${SEDCMD[#]}" lets you expand an array, keeping each element a separate word, without any of the problems you're having.
It does. Try:
#!/bin/bash
RGX='s/^[ \t]*//'
#SED='$RGX'
echo " string" | sed "$RGX"
This works.
The issue you have is with quotes and spaces. Double quoted strings are passed as single arguments.
Add set -x to your script. You'll see that variables within a single-quote mark are not expanded.
+To expand on my comment above:
#!/bin/bash
RGX='s/^[[:space:]]+//'
SED="sed -r '$RGX'"
eval "printf \" \tstring\n\" | $SED"
Note that this also makes your regex an extended one, for no particular reason. :-)