Bash Exit Codes

The exit code is a number between 0 and 255. This is the value returns to parent process after completion of a child process. In other words, it denotes the exit status of the last command our function.

The exit code value return based on a command or program will successfully execute or not.

Success – A zero (0) value represents success.
failure – A non-zero exit-code represents failure.

Example

Write a program to write some content in /tmp/tesfile.txt file and check command executed successfully or not.

#!/bin/bash

echo "hi" > /tmp/tesfile.txt

if [ $? -eq 0 ]; then
  echo "Hurrey. it works"
else
  echo "Sorry, can't write /tmp/tesfile.txt"
fi

#!/bin/bash

echo "hi" > /tmp/tesfile.txt

if [ $? -eq 0 ]; then

echo "Hurrey. it works"

else

echo "Sorry, can't write /tmp/tesfile.txt"

Another Example

Write a programme to search a string in a file and check if string present or not.

#!/bin/bash

STRING="tecadmin"

if grep ${STRING} /etc/passwd
then
  echo "Yeah! string found"
else
  echo "Ooooh, no matching string found"
fi

#!/bin/bash

STRING="tecadmin"

if grep ${STRING} /etc/passwd

then

echo "Yeah! string found"

else

echo "Ooooh, no matching string found"

This program will search if string “tecadmin” present in /etc/passwd file.