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June 1, 2020 19:53
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| #!/usr/bin/env bash | |
| ## bash examples for RH134 - milan santosi | |
| ## intro / explanation | |
| # first line always magic line. it's needed when your O/S can't figure out from file-ending (.bash, .sh). IMHO the best way to find the bash shell interpreter (NOT just "/bin/sh") on any given unix environment (also: Docker environments!) is to ask "env" to return preferred path to bash. 99% of the time it's /usr/bin/bash and/or /bin/bash, but with asking env, we can be sure... | |
| # file endings are optional. It matters more if chmod +x is set. The magic line is most important when script is called as argument of other command (such as `bash myscript.sh`). If script is not in $PATH, use "./" to call: `./script.sh`. Otherwise `echo $PATH` and move script to a directory that's listed. Or don't run script standalone but with `bash myscript.sh` | |
| ## simple if then | |
| # this here is a so-called bashism / very bash-specific syntactic sugar | |
| echo "output of bash-syntax using [[" | |
| [[ $1 = 'fedora' ]] && echo "it's fedora!" || echo "it's not fedora :(" | |
| # the universal, sh-compable syntax for exactly the same task is like this: | |
| echo "output of old sh-syntax using if [" | |
| if [ $1 = 'fedora' ] ; | |
| then echo "it's still fedora!" | |
| else echo "it's still not fedora :((" | |
| fi | |
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