Bash Hash Builtin
The Bash shell hash builtin maintains a hash cache (table) containing the full pathname of previously executed commands that are on your PATH environmental variable. If the command is in the hash...
View ArticleImplementing strstr in Korn Shell
Neither Bash or the Korn Shell 93 (ksh93) provide a C-like strstr builtin. Here is a simple implementation of a strstr function in ksh93. The strstr function finds the first occurrence of s2 in s1. If...
View ArticleDifferences in Variable Scope in Shell Functions
Ksh93 and bash have subtly different scopes for variables defined in shell functions as the following example shows: # POSIX function syntax testme2() { printf "Function testme2 invokedn"...
View ArticleShell String Concatenation
Many people are unaware that string concatenation using the += syntax is fully supported in modern versions of both the Bash and Korn shells Here is a simple example which demonstrates the syntax:...
View ArticleThe Time Keyword in Bash
The word time is one of the bash shell reserved words. It is not a bash shell builtin. $ builtin time bash: builtin: time: not a shell builtin Bash does support the older Bourne shell keyword times as...
View ArticleZero Padding Brace Expansions in the Korn Shell
Both bash and zsh shells support leading zeros in ranges: $ echo {1..10} 1 2 3 4 5 6 7 8 9 10 $ echo {01..10} 01 02 03 04 05 06 07 08 09 10 $ echo {001..010} 001 002 003 004 005 006 007 008 009 010 $...
View ArticleKorn Shell Launcher for Windows Subsystem for Linux
In this post, I show you how to create a Korn Shell launcher for the new Windows Subsystem for Linux.
View ArticleBash-like Customizable Prompt in Korn Shell
Bash has built-in support for extensive PS1 prompt customization and as a result many people customize their shell prompts. There is no equivalent built-in support for PS1 customization in ksh93 but...
View ArticlePrinting Bash or Korn Shell Script Arguments
This post discusses various issues, workarounds and solutions to printing details of arguments (AKA positional parameters) passed to shell scripts via the command line upon invocation of the shell...
View ArticleBash Printf %T Option
This post discusses and demonstrates how to use the printf %T date functionality available in the Bash shell since version 4.2.
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