The Dash shell, a POSIX-compliant derivative of the Almquist shell used as /bin/sh in Debian, Ubuntu and other Linux distributions

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When sh is a symlink to bash or dash, bash limits itself to POSIX-compliance, so it should be 100% compatible with sh?

From Difference between bash and sh: ABck to the question: If you have /bin/sh as a link to bash, then bash will not behave the same when called as /bin/sh as it does when called as /bin/bash. ...
25
votes
3answers
6k views

Is dash or some other shell “faster” than bash?

I always thought that the only benefit of using dash instead of bash was that dash was smaller, and therefore many instances of dash would start faster at boot time. But I have done some research, ...
11
votes
2answers
870 views

What is the difference between : and true?

In bash: $ type : : is a shell builtin $ type true true is a shell builtin Looks like they are the same, but they don't give the same system trace: $ strace : strace: :: command not found $ strace ...
4
votes
2answers
3k views

Calling bash from sh (dash) with commands read from args, and “Unterminated quoted string”/“unexpected EOF”

Just thought I'd document this: I'm trying something very simple - set env variable in bash, and print it out: $ bash -c "a=1; echo a$a;" a $ bash -c "a=1; echo a\$a;" a1 Now I'd want this same ...
1
vote
1answer
90 views

Bash FUNCNAME equivalent in Dash

Bash can print the current function name: $ bash -c 'g(){ echo $FUNCNAME; }; g' g However Dash cannot use FUNCNAME: $ dash -c 'g(){ echo $FUNCNAME; }; g' It is possible to access the current ...
3
votes
1answer
80 views

Export a selection of environment variables with correct escaping

I want to export some environment variables which I set in a dash script to a file: myvariable="line 1 LINE=3 some characters: # \" \$ line 5" myvariable2="abc" export myvariable myvariable2 ...
0
votes
1answer
938 views

POSIX and Bash, sh shorthand, for compound if statement

I prefer to do my sh commands in shorthand, And I prefer to be in POSIX. Truthfully, if the script can run on Dash, that is good enough. Which means using the test command [, not the extended [[. I ...
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1answer
741 views

Some commands not working in bash script

I'm using Ubuntu 14.04.02 32bit. On doing some shell programming, I found out that running the script through the sh command sometimes cause errors. Is it because the sh command is invoking the ...