Partially output commandline screen to file

Question

I'm writing a logfile for a backup solution.

The backup solution is a simple 7-zip update command.

I'd like to log which files it backups. If I use >> log.txt I will get the result, but also lots of other information that 7-zip outputs that I don't want.

I'm looking for a way to partially log what is on the screen. I don't mind to use 7z .... >templog.txt and then doing something to templog.txt before appending it to log.txt. But I don't know how to selectively remove lines from templog.txt from the commandline either.

So I guess my question boils down: How can I remove the first 10 lines from templog.txt or alternatively only redirect part of the output on screen to a logfile?

Bonus question: How to selectively remove lines from templog.txt or the output redirection that are not at the beginning?

Answer 1

How can I remove the first 10 lines from templog.txt or alternatively only redirect part of the output on screen to a logfile?

Below are a couple different ways to accomplish what you ask for omitting lines with certain strings in them with Findstr or else to just remove specific line numbers with SED from templog.txt before it appends what's in it to the full log file of log.txt.

---

Using FINDSTR

^{This will omit the strings in the double-quotes which are in templog.txt from being appended to log.txt}

FINDSTR /V /I "string1 string2 string3 string4" templog.log>>log.txt

^{This will omit the regular expressions in the double-quotes after each /C: switches which are in templog.txt from being appended to log.txt so you'd just have to be sure to have each regular expression which you need to match for omitting.}

FINDSTR /V /R /C:"<regex1>" /C:"<regex2>" /C:"<regex3>" templog.log>>log.txt

---

Using SED

^{This will remove lines 1 - 10 from templog.txt and then after that operation append the rest to log.txt}

sed -i -e "1,10d" templog.txt

---

Further Resources

• Findstr
• SED
• SED for Windows

Answer 2

PowerShell - Remove Specific Lines from a File

^{You can use the below PowerShell commands to skip the first five lines using the -Skip parameter with Select-Object from the content of the templog.txt file, and then update it with everything except those file lines skipped to omit.}

(Get-Content "C:\path\templog.txt" | Select-Object -Skip 5) | Set-Content "C:\path\templog.txt"

---

^{You can use the below PowerShell commands using the -Skip parameter with Select-Object to skip the first five lines of the templog.txt, and then append all but those lines to the log.txt file.}

(Get-Content "C:\path\templog.txt" | Select-Object -Skip 5) | Add-Content "C:\path\log.txt"

---

Further Resources

• Select-Object
• Get-Content
• Set-Content
• Add-Content