How can I read a dash file from the terminal other than delimiting it with ./
For example to read a - file we can read it by
cat ./-file_name
Q: Is there an alternative way to achieve the same thing?
3 Answers
Use double -- to mark end of options:
cat -- -<FILENAME>
Other programs such as touch, rm or git checkout also follow this convention:
$ touch -- -file
$ ll
total 0
-rw-r--r-- 1 ja ja 0 Mar 10 13:13 -file
$ echo hi! >> -file
$ cat -- -file
hi!
$ rm -- -file
$ echo $?
0
WARNING: It's good practice to always use -- after rm in scripts. An attacker could place --rf file in a directory and rm * would take it as run parameters. See this:
$ touch A
$ touch B
$ mkdir dir
$ touch dir/C
$ touch -- -rf
$ rm *
$ ll
total 0
-rw-r--r-- 1 ja ja 0 Mar 10 13:21 -rf
Oops, this is not we meant, we didn't want to remove directories. We should have used --:
$ touch A
$ touch B
$ mkdir dir
$ touch dir/C
$ touch -- -rf
$ rm -- *
rm: cannot remove `dir': Is a directory
$ ll
total 4.0K
drwxr-xr-x 2 ja ja 4.0K Mar 10 13:22 dir
answered Mar 10, 2015 at 12:15
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4You can't count on every program implementing
--: many do but not all. Mar 10, 2015 at 13:44 -
2Really? I didn't say that all programs implement
--, I said showed some that do. Mar 10, 2015 at 13:47 -
1
-
1@vidhan you can also complicate your life for no reason and do something like
find . -name '-file_name' -exec cat {} \;but there really isn't much point to it.– terdon ♦Mar 10, 2015 at 17:50 -
3This doesn't work if the file is named
-and nothing else? This came up in the wargame: overthewire.org/wargames/bandit/bandit2.html May 12, 2017 at 17:29
For commands which get input from stdin, you can use redirection:
cat <-file_name
-
ya this one works :) is so I got 3 ways to read them one by using ./ other by using -- and another by using <, any more ways to do the same thing ??– vidhanMar 10, 2015 at 15:25
Alternatives become weird:
dd if=-x 2>/dev/null
./prefix. It's the most portable (cf the usenet era's Unix FAQ)find . -name "-filename" | xargs catwill send ./-filename through the pipe. For your (simplified?) case a mistake, but it might help in large directories / scripts.