How to Sum a column in AWK?
You could sum the column 57 of your file, and print it using
unix
When could or should I use chmod g+s on a file or directory?
In deploying to a new (Solaris 9) environment recently, one of the steps was to copy a set of files and directories to their new location and then to apply the group UID bit (using “chmod -R g+s”) to all files in the directory tree giving a mode of -rwxr-s— to everything. The result was … Read more
How to get the current directory in a C program?
Have you had a look at getcwd()? Simple example:
Shell script “for” loop syntax
Brace expansion, {x..y} is performed before other expansions, so you cannot use that for variable length sequences. Instead, use the seq 2 $max method as user mob stated. So, for your example it would be:
wait(null) and wait(&status) C language and Status
If you call wait(NULL) (wait(2)), you only wait for any child to terminate. With wait(&status) you wait for a child to terminate but you want to know some information about it’s termination. You can know if the child terminate normally with WIFEXITED(status) for example. status contains information about processes that you can check with some already defined MACRO.
mkdir’s “-p” option
So this doesn’t seem like a terribly complicated question I have, but it’s one I can’t find the answer to. I’m confused about what the -p option does in Unix. I used it for a lab assignment while creating a subdirectory and then another subdirectory within that one. It looked like this: This is in a private … Read more
What do ‘real’, ‘user’ and ‘sys’ mean in the output of time(1)?
Real, User and Sys process time statistics One of these things is not like the other. Real refers to actual elapsed time; User and Sys refer to CPU time used only by the process. Real is wall clock time – time from start to finish of the call. This is all elapsed time including time slices used … Read more
What does it mean to write to stdout in C?
That means that you are printing output on the main output device for the session… whatever that may be. The user’s console, a tty session, a file or who knows what. What that device may be varies depending on how the program is being run and from where. The following command will write to the … Read more
What does ^M character mean in Vim?
Unix uses 0xA for a newline character. Windows uses a combination of two characters: 0xD 0xA. 0xD is the carriage return character. ^M happens to be the way vim displays 0xD (0x0D = 13, M is the 13th letter in the English alphabet). You can remove all the ^M characters by running the following: Where ^M is entered by holding down Ctrl and … Read more
Display exact matches only with grep
You need a more specific expression. Try grep ” OK$” or grep “[0-9]* OK”. You want to choose a pattern that matches what you want, but won’t match what you don’t want. That pattern will depend upon what your whole file contents might look like. You can also do: grep -w “OK” which will only match a whole word “OK”, … Read more