To combine stderr and stdout into the stdout stream, we append this to a command: 2>&1 For example, the following command shows the first few errors from compiling main.cpp: g++ main.cpp 2>&1 | head But what does 2>&1 mean?

Mar 25, 2015 · These are positional arguments of the script. Executing ./script.sh Hello World Will make $0 = ./script.sh $1 = Hello $2 = World Note If you execute ./script.sh, $0 will give output ./script.sh but if you execute it with bash script.sh it will give output script.sh.

Apr 25, 2016 · $# Denotes the number of command line arguments or positional parameters $1 and $2 denote the first and second command line argument passed, respectively

I can't seem to be able to increase the variable value by 1. I have looked at tutorialspoint's Unix / Linux Shell Programming tutorial but it only shows how to add together two variables. I have tr...

Dec 12, 2014 · What do the following environment variables in Linux mean? What is $* (dollar sign followed by an asterisk)? What is $# (dollar sign next to a hash mark/number sign/octothorpe/pound sign)?

Sep 14, 2012 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process which backgrounded myprog...

Apr 3, 2012 · What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options $@

Sep 3, 2017 · The only general convention is that a zero exit status signifies success, whereas any non-zero exit status is a failure. Different non-zero values may indicate the reason for the exit status, usually documented for the particular program. C's <stdlib.h> include file defines two constants: EXIT_FAILURE (1) EXIT_SUCCESS (0) "man-pages (7)" suggests to document the meaning of the exit status in ...

$(command) is “command substitution”. As you seem to understand, it runs the command, captures its output, and inserts that into the command line that contains the $(…); e.g., $ ls -ld $(date +%B).txt -rwxr-xr-x 1 Noob Noob 867 Jul 2 11:09 July.txt ${parameter} is “parameter substitution”. A lot of information can be found in the shell’s man page, bash (1), under the “ …

Oct 9, 2013 · Have you tried #undef linux, or perhaps using a different variable? I think the constant linux is used to test for operating systems e.g. if you're designing a cross-platform application and need to know exactly which API to use (windows, mac, linux, BSD, etc).