You can always check the man page of your shell. man bash says: Special Parameters # Expands to the number of positional parameters in decimal. Therefore a shell script can check …

In shell terminology, eval is a built-in, not a function. In practice, built-ins behave a lot like functions that don't have an in-language definition, but not quite (as becomes apparent if you …

Kernel Version. If you want kernel version information, use uname(1). For example: $ uname -a Linux localhost 3.11.0-3-generic #8-Ubuntu SMP Fri Aug 23 16:49:15 UTC 2013 x86_64 …

On many systems booting into single user mode will give the user access to a root shell without prompting for a password. Notably, systemd-based systems will prompt you for the root …

You can find a very nice reference for bash's [aka test builtin's operators here, or by running help test in a bash shell or info bash test or info bash '[' from any shell¹. If you are using a different …

Better shell solution when blank lines may be piped to wc 1 Set comparator with variables within a variable, then have shell expand those variables each time it's echo'd

It's probably the most common command to use in an if, which can lead to the assumption that it's part of the shell's syntax. But if you want to test whether a command succeeded or not, use …

The echo shows the new directory not the previous one. And I would find it useful, so that I know where I am now, especially if I'm in a shell that only shows the current directory name (or …

Aug 21, 2018 · the shell executioner still said line 1508 has trouble. Next, I made a copy of the original shell script. Deleting a whole bunch of code from the bottom. Then validate my code …

Jun 14, 2013 · Using POSIX shell functions, and awk math power, just define this (one line) function: calc(){ awk "BEGIN { print $*}"; } Then just execute things like calc 1+1 or calc 5/2. …