How to run a shell script on a Unix console or Mac terminal

Question

I know it  forget it and relearn it again  Time to write it down

User · Answer

Little addition  to run an interpreter from the same folder  still using   hashbang in scripts  As example a php7 2 executable copied from  usr bin is in a folder along a hello script      php7 2  lt  php  echo  quot Hello  quot     To run it    hello  Which behave just as equal as    php7 2 hello   The proper solutions with good documentation can be the tools linuxdeploy and or appimage  this is using this method under the hood

User · Answer

For the bourne shell   sh myscript sh   For bash   bash myscript sh

User · Answer

To run a non-executable sh script  use   sh myscript   To run a non-executable bash script  use   bash myscript   To start an executable  which is any file with executable permission   you just specify it by its path    foo bar  bin bar   bar   To make a script executable  give it the necessary permission   chmod  x bar   bar   When a file is executable  the kernel is responsible for figuring out how to execte it   For non-binaries  this is done by looking at the first line of the file   It should contain a hashbang       usr bin env bash   The hashbang tells the kernel what program to run  in this case the command  usr bin env is ran with the argument bash    Then  the script is passed to the program  as second argument  along with all the arguments you gave the script as subsequent arguments   That means every script that is executable should have a hashbang   If it doesn t  you re not telling the kernel what it is  and therefore the kernel doesn t know what program to use to interprete it   It could be bash  perl  python  sh  or something else    In reality  the kernel will often use the user s default shell to interprete the file  which is very dangerous because it might not be the right interpreter at all or it might be able to parse some of it but with subtle behavioural differences such as is the case between sh and bash    A note on  usr bin env  Most commonly  you ll see hash bangs like so      bin bash   The result is that the kernel will run the program  bin bash to interpret the script   Unfortunately  bash is not always shipped by default  and it is not always available in  bin   While on Linux machines it usually is  there are a range of other POSIX machines where bash ships in various locations  such as  usr xpg bin bash or  usr local bin bash   To write a portable bash script  we can therefore not rely on hard-coding the location of the bash program   POSIX already has a mechanism for dealing with that  PATH   The idea is that you install your programs in one of the directories that are in PATH and the system should be able to find your program when you want to run it by name   Sadly  you cannot just do this     bash   The kernel won t  some might  do a PATH search for you   There is a program that can do a PATH search for you  though  it s called env   Luckily  nearly all systems have an env program installed in  usr bin   So we start env using a hardcoded path  which then does a PATH search for bash and runs it so that it can interpret your script      usr bin env bash   This approach has one downside  According to POSIX  the hashbang can have one argument   In this case  we use bash as the argument to the env program   That means we have no space left to pass arguments to bash   So there s no way to convert something like    bin bash -exu to this scheme   You ll have to put set -exu after the hashbang instead   This approach also has another advantage  Some systems may ship with a  bin bash  but the user may not like it  may find it s buggy or outdated  and may have installed his own bash somewhere else   This is often the case on OS X  Macs  where Apple ships an outdated  bin bash and users install an up-to-date  usr local bin bash using something like Homebrew   When you use the env approach which does a PATH search  you take the user s preference into account and use his preferred bash over the one his system shipped with

User · Answer

The file extension  command is assigned to Terminal app  Double-clicking on any  command file will execute it

User · Answer

To start the shell-script  file sh    sh file sh  bash file sh   Another option is set executable permission using chmod command   chmod  x file sh   Now run  sh file as follows     file sh

User · Answer

If you want the script to run in the current shell  e g  you want it to be able to affect your directory or environment  you should say      path to script sh   or   source  path to script sh   Note that  path to script sh can be relative  for instance   bin script sh runs the script sh in the bin directory under the current directory

User · Answer

First  give permission for execution - chmod  x script name     If script is not executable - For running sh script file - sh script name For running bash script file - bash script name If script is executable -   script name   NOTE -you can check if the file is executable or not by using  ls -a

[linux] How to run a shell script on a Unix console or Mac terminal?

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