Difference between revisions of "Sed"
From Linuxintro
imported>ThorstenStaerk |
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sed 's/^[ \t]*//' | sed 's/^[ \t]*//' | ||
* Replace strings | * Replace strings | ||
| − | sed | + | # echo "hello world" | sed "<abbr title="substitute">s</abbr>/world/moon/" |
| + | hello moon | ||
* Insert a line a beginning of file | * Insert a line a beginning of file | ||
sed -i '1i <This is now at the first line>' <filename> | sed -i '1i <This is now at the first line>' <filename> | ||
Latest revision as of 19:31, 7 February 2013
sed is a command to edit a text stream in batch mode.
For example,
sed "s/a/o/"
Will read your input (stream) from the keyboard and substitute every a by an o.
Usecases
- Remove leading white space
sed 's/^[ \t]*//'
- Replace strings
# echo "hello world" | sed "s/world/moon/" hello moon
- Insert a line a beginning of file
sed -i '1i <This is now at the first line>' <filename>
- Replace several newlines by one
sed 's/\ \{1,\}/\ /g'
- change the protocol for a given port in /etc/services:
sed -ri "s/.{16}3200/sapdp00 3200/" /etc/services
Limitations
You cannot use sed to delete linebreaks, for this you must use tr.
