Unix & Linux Weekly Newsletter - Tuesday, July 29, 2014

Top new questions this week: Reverse grepping Let's say, I have a really big text file (about 10.000.000 lines). I need to grep it from the end and save result to a file. What's the most efficient way to accomplish task? / grep / efficiency   asked by сергей 26 votes answered by chaos 27 votes Result of diff two files with switched lines says missing the same line twice I am trying to understand the linux diff command on two files whose lines are just permutation of each other but not able to grok the output that it generates. Consider the three commands below: … / diff   asked by Geek 23 votes answered by chaos 25 votes Is `-` used only with cd? cd - can switch between current dir and previous dir. It seems that I have seen - used as arguments to other commands before, though I don't remember if - means the same as with cd. I found that - … / cd / options / arguments   asked by Tim 17 votes answered by Lawrence 22 votes Does ~ always equal $HOME I know this has probably been asked before, but I couldn't find it with Google. Given Linux Kernel No configurations that change $HOME bash Will ~ == $HOME be true? / bash / shell / environment-variables / home   asked by PythonNut 17 votes answered by Stéphane Chazelas 14 votes How to retrieve lost aliases? Let me start by saying I know this was dumb. Time and Linux make fools of us all. I made an echo command to my .bash_aliases file and erased all of my aliases, except the test alias. However, I … / bash / command-line / alias / bashrc   asked by MrUser 16 votes answered by mikeserv 7 votes How did `git pull` eat my homework? I feel like a kid in the principal's office explaining that the dog ate my homework the night before it was due, but I'm staring some crazy data loss bug in the face and I can't figure out how it … / git / data-recovery / debugging   asked by Caleb 14 votes Find all occurances in a file with sed Using OPEN STEP 4.2 OS... I am currently using the following sed Command: sed -n '1,/141.299.99.1/p' TESTFILE | tail -3 This command will find one instance in a file with the ip of 141.299.99.1 and … / sed   asked by Dale 13 votes answered by steeldriver 3 votes Greatest hits from previous weeks: How to do integer & float calculations, in bash or other languages/frameworks? Using echo "20+5" literally produces the text "20+5" What command can I use to get the numeric sum, e.g. 25 in this case. Also, what's the easiest way to do it just using bash for floating point, … / bash / shell / command-line / calculator / floating-point   asked by Michael Durrant 102 votes answered by lgarzo 127 votes Repeat a Unix command every x seconds forever There's a builtin Unix command repeat whose first argument is the number of times to repeat a command, where the command (with any arguments) is specified by the remaining arguments to repeat. For … / command-line / scripting   asked by dreeves 155 votes answered by Gregor Brandt 205 votes Can you answer these? List Kerberos principals with valid TGTs Is it possible to query my (MIT) Kerberos KDC to return a list of principals who have been issued TGTs that are currently valid? My use case is that I would like to find out which users are currently … / administration / kerberos   asked by Joseph R. 6 votes Typing punctuation adds an accent to the preceding letter after my laptop is docked for a few minutes I am running Manjaro XFCE. Everything worked like a charm for months now, but 2 weeks ago the keyboard configuration from my external keyboard seems damaged. Writing on my laptop itself works … / linux / x11 / keyboard-shortcuts / keyboard-layout   asked by John Optional 3 votes xpra attach failure After entering the command to attach to an xpra session: xpra attach ssh:SERVERNAME:100 we get this response: connection lost: empty marker in read queue Connection lost What does it mean? We … / x11 / xpra   asked by user78863 3 votes

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