Résultats de recherche
27 oct. 2021 · the intent is to execute the command that follows the &&only if the first command is successful. This is idiomatic of Posix shells, and not only found in Bash. It intends to prevent the running of the second process if the first fails. You may notice I've used the word "intent" - that's for good reason.
10 oct. 2010 · Just from reading that I would have never understood that "$@" expands into a list of separate parameters. Whereas, "$*" is one parameter consisting of all the parameters added together. If it still makes no sense, do this. Bash special parameters explained with four example shell scripts. edited Jun 9, 2021 at 21:33.
14 sept. 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...
In bash, && and || have equal precendence and associate to the left. See Section 3.2.3 in the manual for details. So, your example is parsed as $ (echo this || echo that) && echo other And thus only the left-hand side of the or runs, since that succeeds the right-hand side doesn't need to run.
27 sept. 2015 · In bash these are implemented via temp files, usually in the form /tmp/sh-thd.<random string>, while in dash they are implemented as anonymous pipes. This can be observed via tracing system calls with strace command. Replace bash with sh to see how /bin/sh performs this redirection. $ strace -e open,dup2,pipe,write -f bash -c 'cat <<EOF > test ...
1 août 2019 · 380. This is the exit status of the last executed command. For example the command true always returns a status of 0 and false always returns a status of 1: true echo $? # echoes 0 false echo $? # echoes 1. From the manual: (acessible by calling man bash in your shell) Expands to the exit status of the most recently executed foreground pipeline.
3 avr. 2012 · In brief, $@ expands to the arguments passed from the caller to a function or a script. Its meaning is context-dependent: Inside a function, it expands to the arguments passed to such function. If used in a script (outside a function), it expands to the arguments passed to such script. $ cat my-script. #! /bin/sh.
30 sept. 2010 · Bash (see conditional expressions) seems to preempt the classic and POSIX meanings for -a and -o with its own alternative operators that take arguments. With some care, you can use the more modern [[ operator, but be aware that the versions in Bash and Korn Shell (for example) need not be identical.
18 oct. 2013 · 57. The =~ operator is a regular expression match operator. This operator is inspired by Perl's use of the same operator for regular expression matching. The [ [ ]] is treated specially by bash; consider that an augmented version of [ ] construct: [ ] is actually a shell built-in command, which, can actually be implemented as an external command.
18 avr. 2012 · But the difference is: [ -e FILE ] True if FILE exists. This will return true for both /etc/hosts and /dev/null and for directories. [ -f FILE ] True if FILE exists and is a regular file. This will return true for /etc/hosts and false for /dev/null (because it is not a regular file), and false for /dev since it is a directory.
