# 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: --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://devops-collective-inc.gitbook.io/a-unix-person-s-guide-to-powershell/commands-detail-e.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.