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Are shell scripts portable?
Shell scripts are a popular choice for writing small programs that do file manipulation. They are generally portable across platforms, but there are a number of things that can make a shell script work fine on one machine and fail on another.
Is POSIX compliant?
[[ is an extended version of the test command built into some shells, but not part of the same POSIX standard; it includes extra options which you are not using here.
What is a POSIX compliant shell?
POSIX defines the application programming interface (API), along with Unix command line shells and utility interfaces. This ensure software compatibility with flavors of Unix and other operating systems. The POSIX shell is implemented for many UNIX like operating systems.
What is difference between bash and sh?
Like sh, Bash (Bourne Again Shell) is a command language processor and a shell. It’s the default login shell on most Linux distributions. Bash is a superset of sh, which means that Bash supports features of sh and provides more extensions on top of that. Though, most of the commands work similarly as in sh.
Which operating systems are POSIX compliant?
Examples of some POSIX-compliant systems are AIX, HP-UX, Solaris, and MacOS (since 10.5 Leopard). On the other hand, Android, FreeBSD, Linux Distributions, OpenBSD, VMWare, etc., follow most of the POSIX standard, but they are not certified.
Is POSIX a shell?
POSIX Shell is a command line shell for computer operating system which was introduced by IEEE Computer Society. POSIX stands for Portable Operating System Interface. POSIX Shell is based on the standard defined in Portable Operating System Interface (POSIX) – IEEE P1003.
Should I use sh or bash?
Basically bash is sh, with more features and better syntax. Most commands work the same, but they are different. Bash (bash) is one of many available (yet the most commonly used) Unix shells. Bash stands for “Bourne Again SHell”,and is a replacement/improvement of the original Bourne shell (sh).
How do I find the first 10 lines in Unix?
Type the following head command to display first 10 lines of a file named “bar.txt”:
- head -10 bar.txt.
- head -20 bar.txt.
- sed -n 1,10p /etc/group.
- sed -n 1,20p /etc/group.
- awk ‘FNR <= 10’ /etc/passwd.
- awk ‘FNR <= 20’ /etc/passwd.
- perl -ne’1..10 and print’ /etc/passwd.
- perl -ne’1..20 and print’ /etc/passwd.