Skip to main content

"IF" statement test condtions in Shell Script

Following are some "IF" Statement constructs to test conditions provided by the shell:
  • -b file = True if the file exists and is block special file.
  • -c file = True if the file exists and is character special file.
  • -d file = True if the file exists and is a directory.
  • -e file = True if the file exists.
  • -f file = True if the file exists and is a regular file
  • -g file = True if the file exists and the set-group-id bit is set.
  • -k file = True if the files' "sticky" bit is set.
  • -L file = True if the file exists and is a symbolic link.
  • -p file = True if the file exists and is a named pipe.
  • -r file = True if the file exists and is readable.
  • -s file = True if the file exists and its size is greater than zero.
  • -s file = True if the file exists and is a socket.
  • -t fd = True if the file descriptor is opened on a terminal.
  • -u file = True if the file exists and its set-user-id bit is set.
  • -w file = True if the file exists and is writable.
  • -x file = True if the file exists and is executable.
  • -O file = True if the file exists and is owned by the effective user id.
  • -G file = True if the file exists and is owned by the effective group id.
  • file1 –nt file2 = True if file1 is newer, by modification date, than file2.
  • file1 ot file2 = True if file1 is older than file2.
  • file1 ef file2 = True if file1 and file2 have the same device and inode numbers.
  • -z string = True if the length of the string is 0.
  • -n string = True if the length of the string is non-zero.
  • string1 = string2 = True if the strings are equal.
  • string1 != string2 = True if the strings are not equal.
  • !expr = True if the expr evaluates to false.
  • expr1 –a expr2 = True if both expr1 and expr2 are true.
  • expr1 –o expr2 = True is either expr1 or expr2 is true.

    Comments

    Popular posts from this blog

    Exploring Node.js Internals

    I found a great article explaining Node JS internals, must read : https://www.smashingmagazine.com/2020/04/nodejs-internals/ Some other articles : Introduction to Node.js Being an official website, Node.dev explains what Node.js is, as well as its package managers, and lists web frameworks built on top of it. “ JavaScript & Node.js ”,  The Node Beginner Book This book by  Manuel Kiessling  does a fantastic job of explaining Node.js, after warning that JavaScript in the browser is not the same as the one in Node.js, even though both are written in the same language. Beginning Node.js This beginner book goes beyond an explanation of the runtime. It teaches about packages and streams and creating a web server with the Express framework. LibUV This is the official documentation of the supporting C++ code of the Node.js runtime. V8 This is the official documentation of the JavaScript engine that makes it possible to write Node.js with JavaScript.

    Hibernate Object Conversations

    Session methods to use for object conversations Save() A new instance being attached to the session. An insert will be scheduled. Update() Call Update to make a transient object persistent again. It will force a SQL update on the transient object. This is because Hibernate does not know whether the object is dirty or not and to be safe by default schedules an update. This method will throw an exception, if the entity is already registered with the session. - NonUniqueObjectException is thrown. saveOrUpdate() Either a save or an update will be called based on whether the identifier exists or not. No identifier - save is called, else update is called. Or for a better understanding, if the object is transient, then a save is called, if the object is persistent, then an update is called. Reattaching an unmodified instance - If you know for sure that an object is not modified and you just want to make it persistent again - Session.lock(item, LockMode.No