bash - quickly escape any characters string

Question

I'm looking for a utility that can quickly escape a string of characters. This task is so useful but i can't found it.

Lets say for an example:

hisrmline 'h | g -E "^ [0-9]*  exit$"'

If i want to manually escape it, it can be done:

'hisrmline '\''h | g -E "^ [0-9]*  exit$"'\'''

But it's time consuming and not efficient. So i found printf %q:

[xiaobai@xiaobai note]$ printf "%q" hisrmline 'h | g -E "^ [0-9]*  exit$"'
hisrmlineh\ \|\ g\ -E\ \"\^\ \[0-9\]\*\ \ exit\$\"[xiaobai@xiaobai note]$ 
[xiaobai@xiaobai note]$ 

The output is wrong because hisrmlineh was concate together, so i'm narrow down the strings:

[xiaobai@xiaobai note]$ printf "%q" hisrmline 'h'
hisrmlineh[xiaobai@xiaobai note]$ 
[xiaobai@xiaobai note]$ 

What i desired was hisrmline\ \'h\'

This is especially useful on grep:

[xiaobai@xiaobai note]$ HISTTIMEFORMAT=""; history|grep -a --color=auto hisrmline\ \'h
 7856  hisrmline 'hisrmline'
 7857  hisrmline 'hisrmline'
 7882  hisrmline 'h | g -E "^ [0-9]*  exit[ ]*$"'
 7883  hisrmline 'h | g -E "^ [0-9]*  exit[ ]*$"'
 7884  hisrmline 'h | g -E "'
 7885  hisrmline 'h | g '
 7886  hisrmline 'h | g'
 7887  hisrmline 'h |'
 7890  hisrmline 'h | g -E "^ [0-9]*  exit$"'
 7891  hisrmline 'h | g -E "^ [0-9]*  exit$"'
 7905  h|g 'hisrmline 'h | g -E "^ [0-9]*  exit$"''

And grep -F wouldn't make my life easier when deal with nested single quote, i still have to manually escape the single quote '\'':

[xiaobai@xiaobai note]$ HISTTIMEFORMAT=""; history|grep -a --color=auto -F  '[0-9]*  exit$"'\'''
 7889  h|g -aF 'h | g -E "^ [0-9]*  exit$"'
 7890  hisrmline 'h | g -E "^ [0-9]*  exit$"'
 7891  hisrmline 'h | g -E "^ [0-9]*  exit$"'
 7905  h|g 'hisrmline 'h | g -E "^ [0-9]*  exit$"''
 7911  h|g 'hisrmline 'h | g -E "^ [0-9]*  exit$"''
 7912  h|g 'hisrmline '"'"'h | g -E "^ [0-9]*  exit$"'"'"'

Is there any easier way or any existing utility to escape list of any characters string ?

Answer 1

If you quote the command line properly then printf should work e.g.:

printf "%q\n" "hisrmline 'h'"
hisrmline\ \'h\'

Or:

printf "%q\n" "hisrmline 'h | g -E \"^ [0-9]*  exit$\"'"
hisrmline\ \'h\ \|\ g\ -E\ \"\^\ \[0-9\]\*\ \ exit\$\"\'

---

EDIT: You're probably looking for this kind of escaping:

IFS= read -r str<<"EOF"
hisrmline 'h | g -E "^ [0-9]*  exit$"'
EOF

printf "%q\n" "$str"
hisrmline\ \'h\ \|\ g\ -E\ \"\^\ \[0-9\]\*\ \ exit\$\"\'

[UPDATE by @林果皞]

To whom might be interested, EOF have to quoted to prevent expansion, as noted by @bize:

EOF without quoted:

[xiaobai@xiaobai Downloads]$ IFS= read -r str<<EOF
> target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
> EOF
[xiaobai@xiaobai Downloads]$ printf "%q\n" "$str"
target=\'h\ \|\ g\ -E\ -i\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\[\ \]\"\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\$\"\'\;\ history\|grep\ -aF\ \"h\ \|\ g\ -E\ -i\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\[\ \]\"\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\$\"\"\;\ echo\ 73
[xiaobai@xiaobai Downloads]$ 

"EOF" quoted:

[xiaobai@xiaobai Downloads]$ IFS= read -r str<<"EOF"
> target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
> EOF
[xiaobai@xiaobai Downloads]$ printf "%q\n" "$str"
target=\'h\ \|\ g\ -E\ -i\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\[\ \]\"\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\$\"\'\;\ history\|grep\ -aF\ \"\$target\"\;\ echo\ \$\{#target\}
[xiaobai@xiaobai Downloads]$ 

Correct behaviour only when supplied from the output of quoted "EOF":

[xiaobai@xiaobai Downloads]$ h|g -F target=\'h\ \|\ g\ -E\ -i\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\[\ \]\"\ -e\ \"\^\[\ \]+\[0-9\]+\ \ .\*\[\|\&\;\ \]+g\$\"\'\;\ history\|grep\ -aF\ \"\$target\"\;\ echo\ \$\{#target\}
 7721  target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
 7725  target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
 7726  atarget='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
 8297  target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}
 8320  target='h | g -E -i -e "^[ ]+[0-9]+  .*[|&; ]+g[ ]" -e "^[ ]+[0-9]+  .*[|&; ]+g$"'; history|grep -aF "$target"; echo ${#target}

*h is aliased to export HISTTIMEFORMAT=""; history *g is aliased togrep -a --color=auto

Direct use of $ h|g -F "$str" is working too.

When deal with unicode, i have to assign LC_ALL= to empty(i.e LC_ALL="en_US.utf8") before query(history, ls..etc) the source string. Then i have to switch it to LC_ALL=C to make printf %q working correctly.