Set a parent shell’s variable from a subshell

by

The whole point of a subshell is that it doesn’t affect the calling session. In bash a subshell is a child process, other shells differ but even then a variable setting in a subshell does not affect the caller. By definition.

Do you need a subshell? If you just need a group then use braces:

a=3
{ a=4;}
echo $a

gives 4 (be careful of the spaces in that one). Alternatively, write the variable value to stdout and capture it in the caller:

a=3
a=$(a=4;echo $a)
echo $a

avoid using back-ticks “, they are deprecated and can be difficult to read.

More Related Contents:

  1. Variables getting reset after the while read loop that reads from a pipeline
  2. How to pipe multiple commands into a single command in the shell? (sh, bash, …)
  3. When does command substitution spawn more subshells than the same commands in isolation?
  4. Difference between single and double quotes in Bash
  5. Command not found error in Bash variable assignment
  6. How to check if a variable is set in Bash
  7. Shell equality operators (=, ==, -eq)
  8. redirect COPY of stdout to log file from within bash script itself
  9. Shell script to delete directories older than n days
  10. Shell: How to call one shell script from another shell script?
  11. How to redirect output of an entire shell script within the script itself?
  12. Quick-and-dirty way to ensure only one instance of a shell script is running at a time
  13. Process all arguments except the first one (in a bash script)
  14. How to represent multiple conditions in a shell if statement?
  15. How to split one string into multiple strings separated by at least one space in bash shell?
  16. Generating permutations using bash
  17. What is the difference between ${var}, “$var”, and “${var}” in the Bash shell?
  18. What does the Bash operator
  19. Remove duplicate entries in a Bash script [duplicate]
  20. Longest line in a file
  21. Simple method to shuffle the elements of an array in BASH shell?
  22. How to view files in binary from bash?
  23. What does “plus colon” (“+:”) mean in shell script expressions?
  24. How does AND and OR operators work in Bash?
  25. Running shell command that has nested quotes via ssh
  26. Test if a command outputs an empty string
  27. How to split one string into multiple variables in bash shell? [duplicate]
  28. How to reload .bash_profile from the command line
  29. How to effectively abort the execution of a Bash script from a function
  30. How to properly nest Bash backticks

Leave a Comment