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 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
Oct 232010
How to echo a tab in bash?
Answer:
In Bash script, if you want to print out unprintable characters such as tab, you need to use -e flag together with the echo command.
E.g.
echo -e "\tfoo\tbar"Simple environment variable usage in Linux
Answer:
In Linux, the most basic way to set an environment variable is use the "=" operator.
For example:
# foo=bar
# echo $foo
bar
