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- What are the special dollar sign shell variables? - Stack Overflow
In Bash, there appear to be several variables which hold special, consistently-meaning values For instance, myprogram amp;; echo $! will return the PID of the process which backgrounded myprog
- The UNIX® Standard | www. opengroup. org
Single UNIX Specification- “The Standard” The Single UNIX Specification is the standard in which the core interfaces of a UNIX OS are measured The UNIX standard includes a rich feature set, and its core volumes are simultaneously the IEEE Portable Operating System Interface (POSIX) standard and the ISO IEC 9945 standard
- bash - Shell equality operators (=, ==, -eq) - Stack Overflow
It depends on the Test Construct around the operator Your options are double parentheses, double brackets, single brackets, or test If you use ((…)), you are testing arithmetic equality with == as in C: $ (( 1==1 )); echo $? 0 $ (( 1==2 )); echo $? 1 (Note: 0 means true in the Unix sense and a failed test results in a non-zero number ) Using -eq inside of double parentheses is a syntax
- What does the line #! bin sh mean in a UNIX shell script?
When you try to execute a program in unix (one with the executable bit set), the operating system will look at the first few bytes of the file These form the so-called "magic number", which can be used to decide the format of the program and how to execute it
- unix - How to check permissions of a specific directory . . . - Stack . . .
I know that using ls -l "directory directory filename" tells me the permissions of a file How do I do the same on a directory? I could obviously use ls -l on the directory higher in the hierarchy
- unix - How to use echo command to print out content of a text file . . .
I am trying to figure out what is the usage of this command: echo lt; a txt According to text book it should redirect a programs standards input Now I am redirecting a txt to echo but instead of
- unix - Diff files present in two different directories - Stack Overflow
I have two directories with the same list of files I need to compare all the files present in both the directories using the diff command Is there a simple command line option to do it, or do I h
- unix - How to get PID of process by specifying process name and store . . .
a way to avoid the "grep -v grep" is to use "grep <process nam [e]>" so it interpolates the string and the process nam [e] isn't found when the first grep executes, if that makes sense
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