I have a problem, where my script argument, goes from this:
'_rofiarg: -mesg "State: Active:Enabled"'
To this (I strip the _rofiarg: using cut btw):
-mesg '"State:' 'Active:Enabled"'
As you can see, my purposeful double quotes get ignored, and Bash splits them into two words.
I'll rewrite a pseudocode here, as the original script has a lot of local dependencies to my configs.
#script1.sh
# $active and $state have some value, of course
script2.sh \
"_rofiarg: -mesg \"State: $active:$state\"" \
${somearray[#]};
#script2.sh
#Check input for rofi arguments, add them to Args(), all else goes to Data()
for Arg in "$#"; do
if [[ "$Arg" =~ _rofiarg:* ]]; then
Args+=( "$(echo "$Arg" | cut -c 11-)" );
else
Data+=( "$Arg" );
fi;
done;
After this I just pass the ${Args[#]} to the target program, in this case Rofi - like this:
out="$(
printf '%s\n' "${Data[#]}" |
rofi -config $CONF/rofi/config.cfg \
-dmenu -no-custom \
-padding $padd \
${Args[#]};
)";
I've been at this problem for hours. All of my statements about what actually gets passed to which program is logged using set -o xtrace, and I'm at a point, where I think I literally tried all random combinations of single, double, $'', and all other quote types.
The line
${Args[#]};
with the unquoted variable expansion is the point where the coherence between "State: and …" is lost. To prevent that, we have to quote the expansion, but in order to remove the quotes and to separate -mesg from "State: …", we have to evaluate the command; this gives:
out="$(
printf '%s\n' "${Data[#]}" |
eval rofi -config $CONF/rofi/config.cfg \
-dmenu -no-custom \
-padding $padd \
"${Args[#]}"
)"
Related
I have a variable in my bash script whose value is something like this:
~/a/b/c
Note that it is unexpanded tilde. When I do ls -lt on this variable (call it $VAR), I get no such directory. I want to let bash interpret/expand this variable without executing it. In other words, I want bash to run eval but not run the evaluated command. Is this possible in bash?
How did I manage to pass this into my script without expansion? I passed the argument in surrounding it with double quotes.
Try this command to see what I mean:
ls -lt "~"
This is exactly the situation I am in. I want the tilde to be expanded. In other words, what should I replace magic with to make these two commands identical:
ls -lt ~/abc/def/ghi
and
ls -lt $(magic "~/abc/def/ghi")
Note that ~/abc/def/ghi may or may not exist.
If the variable var is input by the user, eval should not be used to expand the tilde using
eval var=$var # Do not use this!
The reason is: the user could by accident (or by purpose) type for example var="$(rm -rf $HOME/)" with possible disastrous consequences.
A better (and safer) way is to use Bash parameter expansion:
var="${var/#\~/$HOME}"
Due to the nature of StackOverflow, I can't just make this answer unaccepted, but in the intervening 5 years since I posted this there have been far better answers than my admittedly rudimentary and pretty bad answer (I was young, don't kill me).
The other solutions in this thread are safer and better solutions. Preferably, I'd go with either of these two:
Charle's Duffy's solution
Håkon Hægland's solution
Original answer for historic purposes (but please don't use this)
If I'm not mistaken, "~" will not be expanded by a bash script in that manner because it is treated as a literal string "~". You can force expansion via eval like this.
#!/bin/bash
homedir=~
eval homedir=$homedir
echo $homedir # prints home path
Alternatively, just use ${HOME} if you want the user's home directory.
Plagarizing myself from a prior answer, to do this robustly without the security risks associated with eval:
expandPath() {
local path
local -a pathElements resultPathElements
IFS=':' read -r -a pathElements <<<"$1"
: "${pathElements[#]}"
for path in "${pathElements[#]}"; do
: "$path"
case $path in
"~+"/*)
path=$PWD/${path#"~+/"}
;;
"~-"/*)
path=$OLDPWD/${path#"~-/"}
;;
"~"/*)
path=$HOME/${path#"~/"}
;;
"~"*)
username=${path%%/*}
username=${username#"~"}
IFS=: read -r _ _ _ _ _ homedir _ < <(getent passwd "$username")
if [[ $path = */* ]]; then
path=${homedir}/${path#*/}
else
path=$homedir
fi
;;
esac
resultPathElements+=( "$path" )
done
local result
printf -v result '%s:' "${resultPathElements[#]}"
printf '%s\n' "${result%:}"
}
...used as...
path=$(expandPath '~/hello')
Alternately, a simpler approach that uses eval carefully:
expandPath() {
case $1 in
~[+-]*)
local content content_q
printf -v content_q '%q' "${1:2}"
eval "content=${1:0:2}${content_q}"
printf '%s\n' "$content"
;;
~*)
local content content_q
printf -v content_q '%q' "${1:1}"
eval "content=~${content_q}"
printf '%s\n' "$content"
;;
*)
printf '%s\n' "$1"
;;
esac
}
How about this:
path=`realpath "$1"`
Or:
path=`readlink -f "$1"`
A safe way to use eval is "$(printf "~/%q" "$dangerous_path")". Note that is bash specific.
#!/bin/bash
relativepath=a/b/c
eval homedir="$(printf "~/%q" "$relativepath")"
echo $homedir # prints home path
See this question for details
Also, note that under zsh this would be as as simple as echo ${~dangerous_path}
Here is a ridiculous solution:
$ echo "echo $var" | bash
An explanation of what this command does:
create a new instance of bash, by... calling bash;
take the string "echo $var" and substitute $var with the value of the variable (thus after the substitution the string will contain the tilde);
take the string produced by step 2 and send it to the instance of bash created in step one, which we do here by calling echo and piping its output with the | character.
Basically the current bash instance we're running takes our place as the user of another bash instance and types in the command "echo ~..." for us.
Expanding (no pun intended) on birryree's and halloleo's answers: The general approach is to use eval, but it comes with some important caveats, namely spaces and output redirection (>) in the variable. The following seems to work for me:
mypath="$1"
if [ -e "`eval echo ${mypath//>}`" ]; then
echo "FOUND $mypath"
else
echo "$mypath NOT FOUND"
fi
Try it with each of the following arguments:
'~'
'~/existing_file'
'~/existing file with spaces'
'~/nonexistant_file'
'~/nonexistant file with spaces'
'~/string containing > redirection'
'~/string containing > redirection > again and >> again'
Explanation
The ${mypath//>} strips out > characters which could clobber a file during the eval.
The eval echo ... is what does the actual tilde expansion
The double-quotes around the -e argument are for support of filenames with spaces.
Perhaps there's a more elegant solution, but this is what I was able to come up with.
why not delve straight into getting the user's home directory with getent?
$ getent passwd mike | cut -d: -f6
/users/mike
I believe this is what you're looking for
magic() { # returns unexpanded tilde express on invalid user
local _safe_path; printf -v _safe_path "%q" "$1"
eval "ln -sf ${_safe_path#\\} /tmp/realpath.$$"
readlink /tmp/realpath.$$
rm -f /tmp/realpath.$$
}
Example usage:
$ magic ~nobody/would/look/here
/var/empty/would/look/here
$ magic ~invalid/this/will/not/expand
~invalid/this/will/not/expand
Here is the POSIX function equivalent of Håkon Hægland's Bash answer
expand_tilde() {
tilde_less="${1#\~/}"
[ "$1" != "$tilde_less" ] && tilde_less="$HOME/$tilde_less"
printf '%s' "$tilde_less"
}
2017-12-10 edit: add '%s' per #CharlesDuffy in the comments.
Here's my solution:
#!/bin/bash
expandTilde()
{
local tilde_re='^(~[A-Za-z0-9_.-]*)(.*)'
local path="$*"
local pathSuffix=
if [[ $path =~ $tilde_re ]]
then
# only use eval on the ~username portion !
path=$(eval echo ${BASH_REMATCH[1]})
pathSuffix=${BASH_REMATCH[2]}
fi
echo "${path}${pathSuffix}"
}
result=$(expandTilde "$1")
echo "Result = $result"
Simplest: replace 'magic' with 'eval echo'.
$ eval echo "~"
/whatever/the/f/the/home/directory/is
Problem: You're going to run into issues with other variables because eval is evil. For instance:
$ # home is /Users/Hacker$(s)
$ s="echo SCARY COMMAND"
$ eval echo $(eval echo "~")
/Users/HackerSCARY COMMAND
Note that the issue of the injection doesn't happen on the first expansion. So if you were to simply replace magic with eval echo, you should be okay. But if you do echo $(eval echo ~), that would be susceptible to injection.
Similarly, if you do eval echo ~ instead of eval echo "~", that would count as twice expanded and therefore injection would be possible right away.
For anyone's reference, a function to mimic python's os.path.expanduser() behavior (no eval usage):
# _expand_homedir_tilde ~/.vim
/root/.vim
# _expand_homedir_tilde ~myuser/.vim
/home/myuser/.vim
# _expand_homedir_tilde ~nonexistent/.vim
~nonexistent/.vim
# _expand_homedir_tilde /full/path
/full/path
And the function:
function _expand_homedir_tilde {
(
set -e
set -u
p="$1"
if [[ "$p" =~ ^~ ]]; then
u=`echo "$p" | sed 's|^~\([a-z0-9_-]*\)/.*|\1|'`
if [ -z "$u" ]; then
u=`whoami`
fi
h=$(set -o pipefail; getent passwd "$u" | cut -d: -f6) || exit 1
p=`echo "$p" | sed "s|^~[a-z0-9_-]*/|${h}/|"`
fi
echo $p
) || echo $1
}
Just to extend birryree's answer for paths with spaces: You cannot use the eval command as is because it seperates evaluation by spaces. One solution is to replace spaces temporarily for the eval command:
mypath="~/a/b/c/Something With Spaces"
expandedpath=${mypath// /_spc_} # replace spaces
eval expandedpath=${expandedpath} # put spaces back
expandedpath=${expandedpath//_spc_/ }
echo "$expandedpath" # prints e.g. /Users/fred/a/b/c/Something With Spaces"
ls -lt "$expandedpath" # outputs dir content
This example relies of course on the assumption that mypath never contains the char sequence "_spc_".
You might find this easier to do in python.
(1) From the unix command line:
python -c 'import os; import sys; print os.path.expanduser(sys.argv[1])' ~/fred
Results in:
/Users/someone/fred
(2) Within a bash script as a one-off - save this as test.sh:
#!/usr/bin/env bash
thepath=$(python -c 'import os; import sys; print os.path.expanduser(sys.argv[1])' $1)
echo $thepath
Running bash ./test.sh results in:
/Users/someone/fred
(3) As a utility - save this as expanduser somewhere on your path, with execute permissions:
#!/usr/bin/env python
import sys
import os
print os.path.expanduser(sys.argv[1])
This could then be used on the command line:
expanduser ~/fred
Or in a script:
#!/usr/bin/env bash
thepath=$(expanduser $1)
echo $thepath
Just use eval correctly: with validation.
case $1${1%%/*} in
([!~]*|"$1"?*[!-+_.[:alnum:]]*|"") ! :;;
(*/*) set "${1%%/*}" "${1#*/}" ;;
(*) set "$1"
esac&& eval "printf '%s\n' $1${2+/\"\$2\"}"
I have done this with variable parameter substitution after reading in the path using read -e (among others). So the user can tab-complete the path, and if the user enters a ~ path it gets sorted.
read -rep "Enter a path: " -i "${testpath}" testpath
testpath="${testpath/#~/${HOME}}"
ls -al "${testpath}"
The added benefit is that if there is no tilde nothing happens to the variable, and if there is a tilde but not in the first position it is also ignored.
(I include the -i for read since I use this in a loop so the user can fix the path if there is a problem.)
for some reason when the string is already quoted only perl saves the day
#val="${val/#\~/$HOME}" # for some reason does not work !!
val=$(echo $val|perl -ne 's|~|'$HOME'|g;print')
I think that
thepath=( ~/abc/def/ghi )
is easier than all the other solutions... or I am missing something? It works even if the path does not really exists.
input in terminal:
cd Desktop
chmod 777 isPalindromeFun.sh
./isPalindromeFun.sh
isPalindrome madam
gives an error: str=madam not found
#!/bin/bash
function isPalindrome () {
if [ "$#" -ne 0 ];
then
inc=$1; # if it has arguments set the increment with the first argument
fi
[ $# -eq 0 ] && { read str ;} || \ str=$*
String="$(echo $str | sed 's/[^[:alnum:]]//g' | \
tr '[:upper:]' '[:lower:]')"
if [ "$(echo $String | rev)" = "$String" ]
then
echo "\"$str\" is a palindrome"
else
echo "\"$str\" is not a palindrome"
fi
}
The backslash needs to be removed when writing this as a single line:
[ "$#" -eq 0 ] && { read str ;} || \ str=$*
It would make more sense if writing the code as two lines:
[ "$#" -eq 0 ] && { read str ;} || \
str=$*
On just one line, however, the backslash only has the effect of escaping the character following it -- making that next character, a space, be data rather than syntax -- and thus makes your command
str=$*
instead be the same as
" str="$*
meaning the space is part of the command. That's not a valid assignment, and of course there's no command called " str=madam" (starting with a space!) on your system.
Aside: $# doesn't strictly need to be quoted -- unless you have IFS set to a value that contains numbers, the results from expanding $# are guaranteed to expand to a single word -- but I'm doing so here as a workaround for StackOverflow's syntax highlighting.
The box has no Ruby/Python/Perl etc.
Only bash, sed, and awk.
A way is to replace chars by map, but it becomes tedious.
Perhaps some built-in functionality i'm not aware of?
Escaping HTML really just involves replacing three characters: <, >, and &. For extra points, you can also replace " and '. So, it's not a long sed script:
sed 's/&/\&/g; s/</\</g; s/>/\>/g; s/"/\"/g; s/'"'"'/\'/g'
Pure bash, no external programs:
function htmlEscape () {
local s
s=${1//&/&}
s=${s//</<}
s=${s//>/>}
s=${s//'"'/"}
printf -- %s "$s"
}
Just simple string substitution.
You can use recode utility:
echo 'He said: "Not sure that - 2<1"' | recode ascii..html
Output:
He said: "Not sure that - 2<1"
or use xmlstar Escape/Unescape special XML characters:
$ echo '<abc&def>'| xml esc
<abc&def>
I'm using jq:
$ echo "2 < 4 is 'TRUE'" | jq -Rr #html
2 < 4 is 'TRUE'
This is an updated answer to miken32 "Pure bash, "no external programs":
bash 5.2 breaks backward compatibility in ways that are highly inconvenient.
From NEWS:
x. New shell option: patsub_replacement. When enabled, a '&' in
the replacement string of the pattern substitution expansion is
replaced by the portion of the string that matched the pattern.
Backslash will escape the '&' and insert a literal '&'.
The option is enabled by default. If you want to restore the previous
behavior, add shopt -u patsub_replacement.
So there is three ways to use miken32 code in bash 5.2+:
Either disable patsub_replacement:
shopt -u patsub_replacement
function htmlEscape () {
local s
s=${1//&/&}
s=${s//</<}
s=${s//>/>}
s=${s//'"'/"}
printf -- %s "$s"
}
, another option is to escape '&' with backslash in the replacement if you want to make it work regardless of the 5.2 feature, patsub_replacement:
function htmlEscape () {
local s
s=${1//&/\&}
s=${s//</\<}
s=${s//>/\>}
s=${s//'"'/\"}
printf -- %s "$s"
}
and another option is to quote string in the replacement:
function htmlEscape () {
local s
s=${1//&/"&"}
s=${s//</"<"}
s=${s//>/">"}
s=${s//'"'/"""}
printf -- %s "$s"
}
There's much better answers, but I just found this so I thought I'd share.
PN=`basename "$0"` # Program name
VER=`echo '$Revision: 1.1 $' | cut -d' ' -f2`
Usage () {
echo >&2 "$PN - encode HTML unsave characters, $VER
usage: $PN [file ...]"
exit 1
}
set -- `getopt h "$#"`
while [ $# -gt 0 ]
do
case "$1" in
--) shift; break;;
-h) Usage;;
-*) Usage;;
*) break;; # First file name
esac
shift
done
sed \
-e 's/&/\&/g' \
-e 's/"/\"/g' \
-e 's/</\</g' \
-e 's/>/\>/g' \
-e 's/„/\ä/g' \
-e 's/Ž/\Ä/g' \
-e 's/”/\ö/g' \
-e 's/™/\Ö/g' \
-e 's//\ü/g' \
-e 's/š/\Ü/g' \
-e 's/á/\ß/g' \
"$#"
The previous sed replacement defaces valid output like
<
into
<
Adding a negative loook-ahead so "&" is only changed into "&" if that "&" isn't already followed by "amp;" fixes that:
sed 's/&(?!amp;)/\&/g; s/</\</g; s/>/\>/g; s/"/\"/g; s/'"'"'/\'/g'
I'm interested to know what this snippet of RSH code does, and whether Bash has something similar:
if [ -z $ALPHA \
-z $BRAVO \
-z $CHARLIE \
-z $DELTA ]; then
var=$ZULU
fi
Those baskslashes are allowing for line continuation. It's as if the code were written like the following:
if [ -z $ALPHA -z $BRAVO -z $CHARLIE -z $DELTA ]; then
var=$ZULU
fi
From man bash
If a \<newline> pair
appears, and the backslash is not itself quoted, the \<newline> is
treated as a line continuation (that
is, it is removed from the input
stream and effectively ignored).
The \ is escaping the end of line.
It is a way to tell that the line is not yet complete and is being continued in the next line.
It just makes your code easier to read.
It is available in bash as well:
$ echo foo
foo
$ echo foo \
> bar
foo bar
$
I have a variable in my bash script whose value is something like this:
~/a/b/c
Note that it is unexpanded tilde. When I do ls -lt on this variable (call it $VAR), I get no such directory. I want to let bash interpret/expand this variable without executing it. In other words, I want bash to run eval but not run the evaluated command. Is this possible in bash?
How did I manage to pass this into my script without expansion? I passed the argument in surrounding it with double quotes.
Try this command to see what I mean:
ls -lt "~"
This is exactly the situation I am in. I want the tilde to be expanded. In other words, what should I replace magic with to make these two commands identical:
ls -lt ~/abc/def/ghi
and
ls -lt $(magic "~/abc/def/ghi")
Note that ~/abc/def/ghi may or may not exist.
If the variable var is input by the user, eval should not be used to expand the tilde using
eval var=$var # Do not use this!
The reason is: the user could by accident (or by purpose) type for example var="$(rm -rf $HOME/)" with possible disastrous consequences.
A better (and safer) way is to use Bash parameter expansion:
var="${var/#\~/$HOME}"
Due to the nature of StackOverflow, I can't just make this answer unaccepted, but in the intervening 5 years since I posted this there have been far better answers than my admittedly rudimentary and pretty bad answer (I was young, don't kill me).
The other solutions in this thread are safer and better solutions. Preferably, I'd go with either of these two:
Charle's Duffy's solution
Håkon Hægland's solution
Original answer for historic purposes (but please don't use this)
If I'm not mistaken, "~" will not be expanded by a bash script in that manner because it is treated as a literal string "~". You can force expansion via eval like this.
#!/bin/bash
homedir=~
eval homedir=$homedir
echo $homedir # prints home path
Alternatively, just use ${HOME} if you want the user's home directory.
Plagarizing myself from a prior answer, to do this robustly without the security risks associated with eval:
expandPath() {
local path
local -a pathElements resultPathElements
IFS=':' read -r -a pathElements <<<"$1"
: "${pathElements[#]}"
for path in "${pathElements[#]}"; do
: "$path"
case $path in
"~+"/*)
path=$PWD/${path#"~+/"}
;;
"~-"/*)
path=$OLDPWD/${path#"~-/"}
;;
"~"/*)
path=$HOME/${path#"~/"}
;;
"~"*)
username=${path%%/*}
username=${username#"~"}
IFS=: read -r _ _ _ _ _ homedir _ < <(getent passwd "$username")
if [[ $path = */* ]]; then
path=${homedir}/${path#*/}
else
path=$homedir
fi
;;
esac
resultPathElements+=( "$path" )
done
local result
printf -v result '%s:' "${resultPathElements[#]}"
printf '%s\n' "${result%:}"
}
...used as...
path=$(expandPath '~/hello')
Alternately, a simpler approach that uses eval carefully:
expandPath() {
case $1 in
~[+-]*)
local content content_q
printf -v content_q '%q' "${1:2}"
eval "content=${1:0:2}${content_q}"
printf '%s\n' "$content"
;;
~*)
local content content_q
printf -v content_q '%q' "${1:1}"
eval "content=~${content_q}"
printf '%s\n' "$content"
;;
*)
printf '%s\n' "$1"
;;
esac
}
How about this:
path=`realpath "$1"`
Or:
path=`readlink -f "$1"`
A safe way to use eval is "$(printf "~/%q" "$dangerous_path")". Note that is bash specific.
#!/bin/bash
relativepath=a/b/c
eval homedir="$(printf "~/%q" "$relativepath")"
echo $homedir # prints home path
See this question for details
Also, note that under zsh this would be as as simple as echo ${~dangerous_path}
Here is a ridiculous solution:
$ echo "echo $var" | bash
An explanation of what this command does:
create a new instance of bash, by... calling bash;
take the string "echo $var" and substitute $var with the value of the variable (thus after the substitution the string will contain the tilde);
take the string produced by step 2 and send it to the instance of bash created in step one, which we do here by calling echo and piping its output with the | character.
Basically the current bash instance we're running takes our place as the user of another bash instance and types in the command "echo ~..." for us.
Expanding (no pun intended) on birryree's and halloleo's answers: The general approach is to use eval, but it comes with some important caveats, namely spaces and output redirection (>) in the variable. The following seems to work for me:
mypath="$1"
if [ -e "`eval echo ${mypath//>}`" ]; then
echo "FOUND $mypath"
else
echo "$mypath NOT FOUND"
fi
Try it with each of the following arguments:
'~'
'~/existing_file'
'~/existing file with spaces'
'~/nonexistant_file'
'~/nonexistant file with spaces'
'~/string containing > redirection'
'~/string containing > redirection > again and >> again'
Explanation
The ${mypath//>} strips out > characters which could clobber a file during the eval.
The eval echo ... is what does the actual tilde expansion
The double-quotes around the -e argument are for support of filenames with spaces.
Perhaps there's a more elegant solution, but this is what I was able to come up with.
why not delve straight into getting the user's home directory with getent?
$ getent passwd mike | cut -d: -f6
/users/mike
I believe this is what you're looking for
magic() { # returns unexpanded tilde express on invalid user
local _safe_path; printf -v _safe_path "%q" "$1"
eval "ln -sf ${_safe_path#\\} /tmp/realpath.$$"
readlink /tmp/realpath.$$
rm -f /tmp/realpath.$$
}
Example usage:
$ magic ~nobody/would/look/here
/var/empty/would/look/here
$ magic ~invalid/this/will/not/expand
~invalid/this/will/not/expand
Here is the POSIX function equivalent of Håkon Hægland's Bash answer
expand_tilde() {
tilde_less="${1#\~/}"
[ "$1" != "$tilde_less" ] && tilde_less="$HOME/$tilde_less"
printf '%s' "$tilde_less"
}
2017-12-10 edit: add '%s' per #CharlesDuffy in the comments.
Here's my solution:
#!/bin/bash
expandTilde()
{
local tilde_re='^(~[A-Za-z0-9_.-]*)(.*)'
local path="$*"
local pathSuffix=
if [[ $path =~ $tilde_re ]]
then
# only use eval on the ~username portion !
path=$(eval echo ${BASH_REMATCH[1]})
pathSuffix=${BASH_REMATCH[2]}
fi
echo "${path}${pathSuffix}"
}
result=$(expandTilde "$1")
echo "Result = $result"
Simplest: replace 'magic' with 'eval echo'.
$ eval echo "~"
/whatever/the/f/the/home/directory/is
Problem: You're going to run into issues with other variables because eval is evil. For instance:
$ # home is /Users/Hacker$(s)
$ s="echo SCARY COMMAND"
$ eval echo $(eval echo "~")
/Users/HackerSCARY COMMAND
Note that the issue of the injection doesn't happen on the first expansion. So if you were to simply replace magic with eval echo, you should be okay. But if you do echo $(eval echo ~), that would be susceptible to injection.
Similarly, if you do eval echo ~ instead of eval echo "~", that would count as twice expanded and therefore injection would be possible right away.
For anyone's reference, a function to mimic python's os.path.expanduser() behavior (no eval usage):
# _expand_homedir_tilde ~/.vim
/root/.vim
# _expand_homedir_tilde ~myuser/.vim
/home/myuser/.vim
# _expand_homedir_tilde ~nonexistent/.vim
~nonexistent/.vim
# _expand_homedir_tilde /full/path
/full/path
And the function:
function _expand_homedir_tilde {
(
set -e
set -u
p="$1"
if [[ "$p" =~ ^~ ]]; then
u=`echo "$p" | sed 's|^~\([a-z0-9_-]*\)/.*|\1|'`
if [ -z "$u" ]; then
u=`whoami`
fi
h=$(set -o pipefail; getent passwd "$u" | cut -d: -f6) || exit 1
p=`echo "$p" | sed "s|^~[a-z0-9_-]*/|${h}/|"`
fi
echo $p
) || echo $1
}
Just to extend birryree's answer for paths with spaces: You cannot use the eval command as is because it seperates evaluation by spaces. One solution is to replace spaces temporarily for the eval command:
mypath="~/a/b/c/Something With Spaces"
expandedpath=${mypath// /_spc_} # replace spaces
eval expandedpath=${expandedpath} # put spaces back
expandedpath=${expandedpath//_spc_/ }
echo "$expandedpath" # prints e.g. /Users/fred/a/b/c/Something With Spaces"
ls -lt "$expandedpath" # outputs dir content
This example relies of course on the assumption that mypath never contains the char sequence "_spc_".
You might find this easier to do in python.
(1) From the unix command line:
python -c 'import os; import sys; print os.path.expanduser(sys.argv[1])' ~/fred
Results in:
/Users/someone/fred
(2) Within a bash script as a one-off - save this as test.sh:
#!/usr/bin/env bash
thepath=$(python -c 'import os; import sys; print os.path.expanduser(sys.argv[1])' $1)
echo $thepath
Running bash ./test.sh results in:
/Users/someone/fred
(3) As a utility - save this as expanduser somewhere on your path, with execute permissions:
#!/usr/bin/env python
import sys
import os
print os.path.expanduser(sys.argv[1])
This could then be used on the command line:
expanduser ~/fred
Or in a script:
#!/usr/bin/env bash
thepath=$(expanduser $1)
echo $thepath
Just use eval correctly: with validation.
case $1${1%%/*} in
([!~]*|"$1"?*[!-+_.[:alnum:]]*|"") ! :;;
(*/*) set "${1%%/*}" "${1#*/}" ;;
(*) set "$1"
esac&& eval "printf '%s\n' $1${2+/\"\$2\"}"
I have done this with variable parameter substitution after reading in the path using read -e (among others). So the user can tab-complete the path, and if the user enters a ~ path it gets sorted.
read -rep "Enter a path: " -i "${testpath}" testpath
testpath="${testpath/#~/${HOME}}"
ls -al "${testpath}"
The added benefit is that if there is no tilde nothing happens to the variable, and if there is a tilde but not in the first position it is also ignored.
(I include the -i for read since I use this in a loop so the user can fix the path if there is a problem.)
for some reason when the string is already quoted only perl saves the day
#val="${val/#\~/$HOME}" # for some reason does not work !!
val=$(echo $val|perl -ne 's|~|'$HOME'|g;print')
I think that
thepath=( ~/abc/def/ghi )
is easier than all the other solutions... or I am missing something? It works even if the path does not really exists.