> For the complete documentation index, see [llms.txt](https://alicenab.gitbook.io/linux/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alicenab.gitbook.io/linux/redhat/tasks/grep-and-sed.md).

# grep and sed

## Task 1:

Find the rows that contain abcde from file /etc/testfile, and write it to the file /tmp/testfile, and the sequence is requested as the same as /etc/testfile

Solution:

```
vim /etc/testfile  # add some lines which contains abcde
grep 'abcde' /etc/testfile > /tmp/testfile
```

## Task 2:

Download the document from `ftp://instructor.example.com/pub/testfile`, find all lines containing `abcde`and redirect to /mnt/answer document, then rearrange the order according the original content.

Solution:

```
wget ftp://instructor.example.com/pub/testfile
grep '[abcde]' /tmp/testfile > /mnt/answer
grep '[abcde]' /tmp/answer
```

## Task 3:

Find all lines in the file /usr/share/mime/packages/freedesktop.org.xml that contain the string ich. Put a copy of these lines in the original order in the file /root/lines. /root/lines should maintain contain no empty lines and all lines must be exact copies of the original lines in `/usr/shre/mime/packages/freedesktop.org.xml`

Solution:

```
grep ich /usr/share/mime/package/freedesktop.org.xml > /root/lines
sed -i '/^$/d' /root/lines
cat /root/lines
```

## Task 4:

Find all lines in the file `/usr/share/dict/words`that contain the string `seismic`. Put a copy of all these lines in their original order in the file `/root/wordlist`. `/root/wordlist`should contain no empty lines and all lines must be exact copies of the original lines in `/usr/share/dict/words`

Solution:

```
grep seismic /usr/share/dict/words > /root/wordlist
sed -i '/^$/d/' /root/wordlist
grep seismic /root/wordlist
```

## Task 5:

Search the string nologin in the `/etc/passwd`file and save the output in `/root/strings`

Solution:

```
grep nologin /etc/passwd > /root/strings
grep nologin /root/strings
```


---

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