Remove part of path on Unix - shell

Question

I'm trying to remove part of the path in a string. I have the path:
/path/to/file/drive/file/path/
I want to remove the first part /path/to/file/drive and produce the output:
file/path/
Note: I have several paths in a while loop, with the same /path/to/file/drive in all of them, but I'm just looking for the 'how to' on removing the desired string.
I found some examples, but I can't get them to work:
echo /path/to/file/drive/file/path/ | sed 's:/path/to/file/drive:\2:'
echo /path/to/file/drive/file/path/ | sed 's:/path/to/file/drive:2'
\2 being the second part of the string and I'm clearly doing something wrong...maybe there is an easier way?

Answer 1

If you wanted to remove a certain NUMBER of path components, you should use cut with -d'/'. For example, if path=/home/dude/some/deepish/dir:
To remove the first two components:
# (Add 2 to the number of components to remove to get the value to pass to -f)
echo $path | cut -d'/' -f4-
# output:
# some/deepish/dir
To keep the first two components:
echo $path | cut -d'/' -f-3
# output:
# /home/dude
To remove the last two components (rev reverses the string):
echo $path | rev | cut -d'/' -f4- | rev
# output:
# /home/dude/some
To keep the last three components:
echo $path | rev | cut -d'/' -f-3 | rev
# output:
# some/deepish/dir
Or, if you want to remove everything before a particular component, sed would work:
echo $path | sed 's/.*\(some\)/\1/g'
# output:
# some/deepish/dir
Or after a particular component:
echo $path | sed 's/\(dude\).*/\1/g'
# output:
# /home/dude
It's even easier if you don't want to keep the component you're specifying:
echo $path | sed 's/some.*//g'
# output:
# /home/dude/
And if you want to be consistent you can match the trailing slash too:
echo $path | sed 's/\/some.*//g'
# output:
# /home/dude
Of course, if you're matching several slashes, you should switch the sed delimiter:
echo $path | sed 's!/some.*!!g'
# output:
# /home/dude
Note that these examples all use absolute paths, you'll have to play around to make them work with relative paths.

Answer 2

You can also use POSIX shell variable expansion to do this.
path=/path/to/file/drive/file/path/
echo ${path#/path/to/file/drive/}
The #.. part strips off a leading matching string when the variable is expanded; this is especially useful if your strings are already in shell variables, like if you're using a for loop. You can strip matching strings (e.g., an extension) from the end of a variable also, using %.... See the bash man page for the gory details.

Answer 3

If you don't want to hardcode the part you're removing:
$ s='/path/to/file/drive/file/path/'
$ echo ${s#$(dirname "$(dirname "$s")")/}
file/path/

Answer 4

One way to do this with sed is
echo /path/to/file/drive/file/path/ | sed 's:^/path/to/file/drive/::'

Answer 5

If you want to remove the first N parts of the path, you could of course use N calls to dirname, as in glenn's answer, but it's probably easier to use globbing:
path=/path/to/file/drive/file/path/
echo "${path#*/*/*/*/*/}" # file/path/
Specifically, ${path#*/*/*/*/*/} means "return $path minus the shortest prefix that contains 5 slashes".

Answer 6

Using ${path#/path/to/file/drive/} as suggested by evil otto is certainly the typical/best way to do this, but since there are many sed suggestions it is worth pointing out that sed is overkill if you are working with a fixed string. You can also do:
echo $PATH | cut -b 21-
To discard the first 20 characters. Similarly, you can use ${PATH:20} in bash or $PATH[20,-1] in zsh.

Answer 7

Pure bash, without hard coding the answer
basenames()
{
local d="${2}"
for ((x=0; x<"${1}"; x++)); do
d="${d%/*}"
done
echo "${2#"${d}"/}"
}
Argument 1 - How many levels do you want to keep (2 in the original question)
Argument 2 - The full path
Taken from vsi_common(original version)

Answer 8

Here's a solution using simple bash syntax that accommodates variables (in case you don't want to hard code full paths), removes the need for piping stdin to sed, and includes a for loop, for good measure:
FULLPATH="/path/to/file/drive/file/path/"
SUBPATH="/path/to/file/drive/"
for i in $FULLPATH;
do
echo ${i#$SUBPATH}
done
as mentioned above by #evil otto, the # symbol is used to remove a prefix in this scenario.