Linux/Unix tools for editing text files
Get the first or last lines of file
Commands head
and tail
prints on screen the first or last ten lines of
given text file. The number of lines can be specified as an option.
For example, the first line can be printed on screen with command:
head -1 tpc2345.tac
Output can be redirected to a new file, deleting any existing file:
head -1 tpc2345.tac > firstline.txt
, or appended to an existing (or new) file:
head -1 tpc2346.tac >> firstline.txt
Remove certain line(s) of a file
Specified line number can be easily deleted using sed
.
For example, line 3 can be deleted with command:
sed -i '3 d' tpc8765ap.bld
, or lines 2-4 could be deleted with command:
sed -i '2,4 d' tpc8765ap.bld
Remove comment line(s)
Data files often contain comment lines starting with '#'-character. If you need to make a new file without the comment lines, enter command:
sed '/^#/ d' < original.dat > new.dat
Replace a word with another word
All instances of a word can be replaced with another word also with sed
.
For example, to replace all instances of 'center' with 'centre' in file tpc.html
,
whether those are parts of words or separate words, enter command:
sed -e 's/center/centre/g' tpc.html
To replace only instances of entire words, we can use word boundary marker '\b', for example:
sed -e 's/\bcenter\b/centre/g' tpc.html
See also:
- Using command-line SW in TPC
- Analysis of PET studies in batch mode
- Download TPC CLI SW
- Windows Subsystem for Linux
Tags: Script, Shell, CLI, Linux
Updated at: 2017-10-13
Created at: 2015-01-08
Written by: Vesa Oikonen