Dec 14, 2024 · Bash is superset of sh. Bash supports sh. POSIX is a set of standards defining how POSIX-compliant systems should work. Bash is not actually a POSIX compliant shell. In a scripting language we denote the interpreter as #!/bin/bash. Analogy: Shell is like an interface or specifications or API. sh is a class which implements the Shell interface.

Actually, even though /bin/sh may be a link to /bin/bash, if started up as sh it behaves differently. From the bash manpage: If bash is invoked with the name sh, it tries to mimic the startup behavior of historical versions of sh as closely as possible, while conforming to the POSIX standard as well. So as sh, it tries to emulate historical sh ...

This shows that 'sh' is a symlink to 'dash', and that /bin/bash, which is the default interactive shell on Ubuntu, is an executable that is almost 9 time bigger than /bin/sh. Indeed, 'man sh' (1590 lines) vs 'man bash' (5459 lines) reveals that bash is a large superset of the traditional 'sh'. Read more here: bash on wikipedia; dash on wikipedia

May 25, 2012 · In addition to the previous answers, even if /bin/sh is a symbolic link to /bin/bash, #!/bin/sh is not totally equivalent to #!/bin/bash. From the bash(1) man page : "If bash is invoked with the name sh, it tries to mimic the startup behavior of historical versions of sh as closely as possible, while conforming to the POSIX standard as well."

Aug 13, 2015 · In particular, GNU Bash is perhaps the most commonly used shell these days. It implements the same features as the Bourne shell, plus a number of extensions. A Bourne shell script typically starts with "Shebang" line: #!/bin/sh A Bash script typically starts with a Shebang that specifies the Bash shell: #!/bin/bash

And the answer is that sh is name for very popular shell. But outdated and replaced by others. Nowadays sh is linked to others shells installed on machine. e.g. I have bash putted there. Running any shell from sh usually trigger some 'compatibility' mode with original 'shell' behavior. So solution is quite simple.

[[is a bash is bash-specific, though others shells may have implemented similar constructs. Don't expect it in an old-school UNIX sh. == and != apply bash pattern matching rules, see "Pattern Matching" in man bash; has a =~ regex match operator; allows use of parentheses and the !, &&, and || logical operators within the brackets to combine ...

Oct 11, 2016 · On different systems, /bin/sh might be a link to ash, bash, dash, ksh, zsh, &c. (It will always be sh-compatible though – never csh or fish.) As long as you stick to sh features only, you can (and probably even should) use #!/bin/sh and …

(From the Bash man page: "Any part of the pattern may be quoted to force it to be matched as a string."). Here in Bash, the two statements yielding "yes" are pattern matching, other three are string equality:

May 27, 2011 · Bash/sh - difference between && and ; Ask Question Asked 13 years, 10 months ago. Modified 7 years, 10 ...