grep command in unix with example

Admin — Fri, 15 Jan 2010 08:24:44 +0000

Grep command is very useful in UNIX.Grep searches for similar pattern on file and return the result.Example of grep command is
grep ‘word’ filename – Will return the line which contain word.
grep -i ‘nocase’ filename – This option will make grep case insensitive.
grep – r ‘sear’ /etc/ – This will search in the whole directory recursively
grep “boo” filename – This will display line which contain exact match of the word boo.
egrep -w ‘word1|word2′ filename – This will search for both the word1 and word2 in the filename.
grep – c word1 filename – Will return the number of lines where word1 is found.
grep -v word1 filename – Will return the line which doesn’t contain the word1.
grep word1 * – Will search for occurence of word1 in whole directory
grep ^a.ad fruitlist.txt – Print line that contain the letter followed by a and in last contain letter ad.

File Compression and archival in UNIX

Admin — Fri, 15 Jan 2010 07:23:56 +0000

There are lot of times when you need to compress and archive files in UNIX in data warehousing project.The reason for this is files in DWH are huge.In this article I will explain how to compress files and than archive them.Files compression is not useful for small files.There are few command and utilities you can use to compress files.They are as follows

1. compress
2. gzip
3. tar(with c option) – Arcchives files without compression
Archive may contain one or more files.Generally archival is done for files which are not used much.

The command to decompress are as follows respectively
1.uncompress
2. gunzip
3. tar(with x option)

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grep command in unix with example

File Compression and archival in UNIX