> For the complete documentation index, see [llms.txt](https://devops-collective-inc.gitbook.io/a-unix-person-s-guide-to-powershell/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://devops-collective-inc.gitbook.io/a-unix-person-s-guide-to-powershell/commands-detail-e.md). # Command Detail - E ## echo `echo` is an alias in PowerShell. As you would expect it's an alias for the closest equivalent to the Linux `echo`: * `write-output` You use it as follows: ``` write-output "Blue is the colour" ``` As well as write-output there are a couple of options for use in Powershell scripts and functions: * `write-debug` * `write-verbose` Whether these produce any output is controlled by commandline or environment flags. ## echo -n In bash, `echo -n` echoes back the string without printing a newline, so if you do this: ``` $ echo -n Blue is the colour ``` you get: ``` Blue is the colour$ ``` ....with your cursor ending up on the same line as the output, just after the dollar prompt Powershell has an exact equivalent of 'echo -n'. If you type: ``` PS C:\Users\matt> write-host -nonewline "Blue is the colour" ``` ....then you get this: ``` PS C:\Users\matt> write-host -nonewline "Blue is the colour" Blue is the colourPS C:\Users\matt> ``` Note that `-nonewline` doesn't 'work' if you're in the ISE. ## egrep The best PowerShell equivalent to `egrep` or `grep` is `select-string`: ``` select-string stamford blue_flag.txt ``` A nice feature of `select-string` which *isn't* available in `grep` is the `-context` option. The -context switch allows you to see a specified number of lines either side of the matching one. I think this is similar to `SEARCH /WINDOW` option in DCL. ## egrep -i Powershell is case-insensitive by default, so: ``` select-string stamford blue_flag.txt ``` ...would return: ``` blue_flag.txt:3:From Stamford Bridge to Wembley ``` If you want to do a case sensitive search, then you can use: ``` select-string -casesensitive stamford blue_flag.txt ``` ## egrep -v The Powershell equivalent to the `-v` option would be `-notmatch` ``` select-string -notmatch stamford blue_flag.txt ``` ## egrep 'this|that' To search for more than one string within a file in bash, you use the syntax: ``` egrep 'blue|stamford' blue_flag.txt ``` This will return lines which contain either 'blue' or 'stamford'. The PowerShell equivalent is to seperate the two strings with a comma, so: ``` $ select-string stamford,blue blue_flag.txt ``` ...returns: ``` blue_flag.txt:2:We'll keep the blue flag flying high blue_flag.txt:3:From Stamford Bridge to Wembley blue_flag.txt:4:We'll keep the blue flag flying high ``` ## | egrep -i sql This is an interesting one, in that it points up a conceptual difference between PowerShell and Bash. In bash, if you want to pipe into a grep, you would do this: ``` ps -ef | egrep sql ``` This would show you all the processes which include the string 'sql' somewhere in the line returned by `ps`. The egrep is searching across the whole line. If the username is 'mr\_sql' then a line would be returned, and if the process is 'sqlplus' than a line would also be returned. To do something similar in PowerShell you would do something more specific ``` get-process | where processname -like '*sql*' ``` So the string 'sql' has to match the contents of the property `processname`. As it happens, get-process by default only returns one text field, so in this case it's relatively academic, but hopefully it illustrates the point. ## env The Linux 'env' shows all the environment variables. In PowerShell there are two set of environment variables: * windows-level variables and * Powershell-level variable Windows-level variables are given by: ``` Get-ChildItem Env: | fl ``` PowerShell-level variables are given by: ``` get-variable ``` ## errpt I think errpt is possibly just an AIX thing (the linux equivalent is, I think, looking at `/var/log/message`). It shows system error and log messages. The PowerShell equivalent would be to look at the Windows eventlog, as follows ``` get-eventlog -computername bigserver -logname application -newest 15 ``` The lognames that I typically look at are 'system', 'application' or 'security'. ## export PS1="$ " In bash the following changes the prompt when you are at the command line ``` export PS1="$ " ``` The Powershell equivalent to this is: ``` function prompt { "$ " } ``` I found this on Richard Siddaway's blog: