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Shell commands notation

Shell

  • echo - $$– Displays current shell process
  • $? – Prints the exit value of the command to the screen
  • Exit code 0– Means command completed successfully
  • $! – PID of last job run in background
  • $* – Expands all parameters passed
  • $$ – Contains current process ID
  • $@ – Each passed parameter expands to a different word
  • $0 – Show the name of the shell or script
  • $_ – Set at shell startup and contains the absolute file name of the shell/script being execute; expands last argument to the previous command