Bash - Continue output on same line. Linux - How to set a BASH variable equal to the output from a command. Tutorial: Conditions in bash scripting (if statements) « Linux Tutorial Blog. If you use bash for scripting you will undoubtedly have to use conditions a lot, for example for an if … then construct or a while loop. The syntax of these conditions can seem a bit daunting to learn and use.
This tutorial aims to help the reader understanding conditions in bash, and provides a comprehensive list of the possibilities. A small amount of general shell knowledge is assumed. Difficulty: Basic – Medium Introduction Bash features a lot of built-in checks and comparisons, coming in quite handy in many situations. You’ve probably seen if statements like the following before: if [ $foo -ge 3 ]; then The condition in this example is essentially a command.
If test $foo -ge 3; then If $foo is Greater then or Equal to 3, the block after ‘then’ will be executed. If [ -f regularfile ]; then The above condition is true if the file ‘regularfile’ exists and is a regular file. If [ -r readablefile]; then The above condition is true if the file ‘readablefile’ exists and is readable. 1. 2. 3. Shell script to get the time difference. Q. I am able to write PHP or Perl script where I can find out time difference between script executions. Now I have .shtml file that is nothing but a shell script outputting some data to browser. What I want is time difference or time it took to execute a script. How do I write a shell script? A. Your Logic should be as follows: * Get start time and store to a variable START * Execute a shell script * Grab output and send to web browser * Get time again and store to a variable END * Calculate difference using expression END - START Here is small script that does the same thing (please note that script teated on GNU/Linux and with GNU date command only): $ vi timediff.bash Append text as follows: #!
Save and execute the script as follows: $ chmod +x timediff.bash Execute the script: $ . It took 4 seconds.