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Tag: linux
Iterate Variables of array into command which itself is a variable bash
I am almost there, the “$i” is where I am having trouble. I have tried ${i}, “$i”, $i. I am sure someone with more experience can help me here I have been working on this for 1 full day. Driving me nuts. Answer That $i is expanded at the moment you define the sts array. After that, it …
How to run iterations asynchronously in shell script
I have a few .csv files like below. xyz0900@1#-1637746436.csv xxx0900@1#-1637746436.csv zzz0900@2#-1637746439.csv yyy0900@1#-1637746436.csv sss0900@2#-1637746439.csv I have written a script to perform below tasks: Get the large file based on the pattern which we have passed as a argument to the script. Merge …
Which OS / platforms implement wait morphing optimization?
Which major OS / platforms implement wait morphing? This question came up when I noticed that there’s no clearcut best practice about whether one should signal a condition variable with mutex locked or not. A typical recommendation is to signal while holding the lock unless profiling shows a substantial…
How to parse a particular MAC address from DHCP lease file in Openwrt?
I am trying to write a script to parse some of devices from DHCP lease file in Openwrt with corresponding addresses . I am maintain a list with some vendor MAC address . When i connect a device to the router , i want to fetch the IP address ,MAC address and Name of that device using the vendor MAC
ELF label address
I have the following code in .s file: Its object file has the following: After linking, it becomes: How does the argument 0x0 to pushq at byte 20 of the object file gets converted to 0x400578 in the final executable? Which section of the object file contains this information? Answer You answered your own ques…
Grep Pattern matching- underline
I’ve not been able to find anything online to help so hoping someone may have an idea. What does an underline in an expression mean when using grep? For example: [_a-zA-Z0-9] Could someone help to explain the purpose here? Answer The grep command uses a regular expression as it is also described in the …
Find the average of multiple columns for each distinct variable in column 1
Hi I have a file with 6 columns and I wish to know the average of three of these (columns 2,3,4) and the sum of the last two (columns 5 and 6) for each unique variable in column one. I have come across code that will get the average for column 2 based on column one but is there anyway
Raw clone system call not working correctly
I’m trying to use the raw clone system call to avoid having to refactor the pid 0 code into a function. Linux requires stacks to by 16 bytes, additionally, libc reserves 16 bits presumably to store ptid and ctid. The code below creates an aligned stack then exits from the child. After waiting for the ch…
Generate a report using awk
I have /etc/fstab entries on 100 servers and i’m trying to write a awk script to identify following. What i need is, first my awk script need to print the domain name, then it should print tools incorrectly mounted on store and is not valid, but kdump01 mounted correctly on kdump , ops mounted correctly…