Check if a file exist in Bash Shell
Answer:
The following script demonstrates how to check if a file exist, using shell (Bash) script
#!/bin/bash
if [ -e test.txt ]
then
echo 'The file exists.'
else
echo 'The file does not exist.'
fi
How to add a directory into the PATH environment variable?
Answer:
To add a new directory into the PATH environment variable, you can use the following command.
# export PATH=$PATH:/opt/myprogram/bin
If you want to have this path being set automatically, then follow this article.
How to echo string to standard error (stderr)?
Answer:
To echo string to the standard error (stderr), rather than the standard output (stdout), you can define the following function in your shell (put in your ~/.bashrc file)
# function echo2() { echo "$@" 1>&2; }
Then you can execute the command like:
# echo2 test
Jun 012011
Simple for loop in Bash shell
Answer:
A simple for loop in Bash shell would like the following. You can use it wisely to skip a lot of repetitive tasks.
#!/bin/bash
for i in {1..10}
do
echo "I am command No. $i"
done
Printing the exclamation mark using echo
Answer:
You might observed a problem when you try to print the exclamation mark (!) using the echo command
E.g.
# echo "test!"
-bash: !": event not foundTo solve it, you can use single quote instead
# echo 'test!'
test!
