The tcpdump arguments are just an example.

Using sed to extract lines in a text file If you write bash scripts a lot, you are bound to run into a situation where you want to extract some lines from a file. Yesterday, I needed to extract the first line of a file, say named somefile.txt. cat somefile.txt Line 1 Line 2 Line 3 Line 4 This specific task can be easily done with this: head -1 somefile.txt Line 1 For a more complicated task, like extract the second to third lines of a file. head is inadequate. So, let's try extracting lines using sed: the stream editor. My first attempt uses the p sed command (for print): sed 1p somefile.txt Line 1 Line 1 Line 2 Line 3 Line 4 Note that it prints the whole file, with the first line printed twice. Why? The default output behavior is to print every line of the input file stream. The explicit 1p command just tells it to print the first line .... again. To fix it, you need to suppress the default output (using -n), making explicit prints the only way to print to default output. sed -n 1p somefile.txt Line 1 Alternatively, you can tell sed to delete all but the first line. sed '1!d' somefile.txt Line 1 '1!d' means if a line is not(!) the first line, delete. Note that the single quotes are necessary. Otherwise, the !d will bring back the last command you executed that starts with the letter d. To extract a range of lines, say lines 2 to 4, you can execute either of the following: sed -n 2,4p somefile.txt sed '2,4!d' somefile.txt Note that the comma specifies a range (from the line before the comma to the line after). What if the lines you want to extract are not in sequence, say lines 1 to 2, and line 4? sed -n -e 1,2p -e 4p somefile.txt Line 1 Line 2 Line 4 Show Sample Output

If your version of curl does not support the --compressed option, use curl -s http://funnyjunk.com | gunzip instead of curl -s --compressed http://funnyjunk.com

nothing special Show Sample Output

Use matched data and some other as replacement data Show Sample Output

Can't print correctly in the command field. There is a new line before } as follows seq 20 | sed -n '5,6 { w out.txt }' Show Sample Output

In case sed and awk are not available you may use this to remove the last character from a string with "rev" and "cut". Show Sample Output

Helps if you accidentally deleted files from an svn repo with plain rm and you would like to mark them for svn to delete too.

Uses sed with a regex to move the linenumbers to the line end. The plain regex (w/o escapes) looks like that: ^([^:]*):(.*) Show Sample Output

sed '4~5,+1d' file.txt 1 2 3 6 7 8 Show Sample Output

Just an other solution :)

Remove ANSI colors from stream or file

reverse of my previous command 10006 Show Sample Output

It remove the square bracket and convert UNIX time to human readable time for all line of a stream (or file). Show Sample Output

Not figured by me, but a colleague of mine. See the total amount of data on an AIX machine. Show Sample Output

Delete range of lines. Ex: Line 6 through 66 in .

Simpler and without all of the coloring gimmicks. This just returns a list of branches with the most recent first. This should be useful for cleaning your remotes. Show Sample Output

This was done in csh. Show Sample Output

Shows sorted by query time, the headers of mysqlbinlog entries. Then is easy to locate the heavier events on the raw log dump Show Sample Output

Show the crontabs of all the users. Show Sample Output

This probably only works without modifications in RHEL/CentOS/Fedora. Show Sample Output